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Home < education < science_fairs < Genesis Energy National Science & Technology Fair 2000 investigations (1)

Genesis Energy National Science & Technology Fair 2000 investigations (1)

Part 1 | Part 2

Sarah Boyd

THE SOUTH ISLAND PIED OYSTER CATCHER

AUCKLAND CITY

ST CUTHBERT'S COLLEGE

During the summer of 1999/2000 I noticed flocks of south Island Pied Oystercatchers feeding continuously on juvenile toheroa found on Ripiro Beach, near Dargaville in Northland. Six months later they had taught themselves how to feed on large mature toheroa without having to extract these heavy shellfish from the sand. While these wading birds have been previously observed on this 100km long exposed west coast beach, this year they have appeared in far greater numbers than seen in previous years. The purpose of my research was to document the devastating effect this new predator is having on New Zealand's unique bivalve shellfish.

As it is illegal to dig or disturb toheroa, I sought permission from the local Iwi responsible, and fortunately I was granted a permit allowing me to conduct my study. Initially I spent several days travelling up and down the beach photographing and watching the feeding technique of South Island Pied Oystercatchers. I discovered it is quite easy to identify whether the toheroa had been eaten by a South Island Pied Oystercatcher or a seagull by the markings left on the sand. Seagulls extract the complete toheroa from the sand, then break open the shellfish by dropping it from height to expose the flesh inside. South Island Pied Oystercatchers thrust their long sharp beaks into the spine muscle of the toheroa then suck out the flesh, leaving the emptied toheroa shell still buried in the sand.

I was fascinated to note that the feeding behaviour of the established Black-Backed and Red-Billed gull population has changed since the arrival of South Island Pied Oystercatchers. Instead of being the aggressive predators of toheroa that I observed only last year, these two species of gull seem to be happy to let the oystercatchers do the work, then they wait and feed on any leftovers.

To survey the actual toheroa mortalities caused by South Island Pied Oystercatchers over one tide change I selected a large toheroa bed 1km north of Glinks Gully. Juvenile toheroa migrate from high water mark down to mid-tide as they mature so to obtain a reasonable cross section of the beach I dug out an area of 1m2 at 30m, 35m and 40m from high tide. I counted and measured all toheroa found then carefully replanted all live animals back into the bed. Of the 269 toheroa I dug out from these positions, 53 or 20% had been eaten by South Island Pied Oystercatchers. I was surprised at this high mortality rate as I believe this represented only a couple of days feeding.

I noted that normal tidal wave action eventually lifts the dead toheroa shells from the sand and deposits them at high water mark. In just a few minutes, at my survey site, I collected 378 emptied toheroa with both valves still hinged. These ranged in length from 20mm-120mm, indicating these birds are causing damage to juvenile and scarce breeding stocks.

Recent published surveys of the New Zealand South Island Pied Oystercatcher population confirm a dramatic increase in numbers since these birds became protected in 1940. I suggest that previous traditional food sources can no longer cope with this population increase leaving these oystercatchers no option but to find additional feeding grounds such as the toheroa beds on Ripiro Beach.

This coming summer, to confirm information given to me by local residents, I intend to try and obtain evidence proving South island Pied Oystercatchers have started a breeding colony in the Kaipara Harbour. Traditionally, each year these birds migrate back to inland riverbeds of the South Island to breed.

Peter Lau

SUBTERRANEAN CONDUCTION

AUCKLAND CITY

MT ROSKILL GRAMMAR

The research began as a part of my hobby of electronic construction. I came across the idea of transmitting electrical signals through the ground to communicate while looking for amateur radio circuits on the internet. To me this idea was previously unheard of and quite intriguing, so I took up the challenge to make it work and to examine how well it works.

I began by researching the behaviour of current flows through the ground. It appears this technique is currently employed as a tool in geophysical exploration to probe for underground features. However, there was little mention of communication via this means. Apparently it had been considered a century ago with the crude electrical equipment of the day, but rarely after the birth of radio. I was keen to find out how modern electronic technology with far greater sensitivity can be applied to the same situation.

In order to establish my hypothesis, I needed a quantitative understanding of the flow of current through the ground, albeit a simplified and idealised one. I realised a qualitative educated guess, as has been employed in the junior levels, is no longer sufficient. I studied the basic textbook electric field and current physics. After much confusion at first and correspondence with mentors over the internet, the problem was finally solved and I had derived the wanted equation.

The next step is to establish what experiments to perform. I noted all the variables and chose to focus on the various distances and separations involved. The level of distortion was also on the agenda. The theoretical model was applied to give predictions where possible. For the less straight-forward experiments, the logic of the situation was worked through, with the aid of diagrams and analogies, to yield an estimation. I was careful to consider only trends and relationships, but not absolute figures. This is because the performance of the system is expected to vary depending on the soil condition - which is circumstantial and uncontrollable.

Given the time constraints, the actual apparatus used to send the transmissions is based on simplicity. A straightforward amplifier circuit was modified to form the transmitter operating off batteries. For amplitude measurements, a pure sine wave was generated by a Wien-Bridge oscillator. The collected signal was filtered before being measured by an electronic voltmeter. For distortion measurement, additional equipment was necessary. This came in the form of a minimalist data logger based on a 286 laptop and a piece of spectrum analysis software acquired off the internet. Four metal probes were used; current flow between the transmitter electrodes can be picked up by the receiving electrodes.

The experiments were performed at a local park. The limited power output of the transmitter meant the range was realistically limited to 100m. For practical purposes, all experiments but that of distortion measurement experiment were performed over a short range.

The key final finding is that ground conduction is a viable form of communication over short distances (500m to 1km). The electrodes should be separated as much as practically allowed to improve performance and the electrode arrangements should face each other. Finally distortion, mainly in the form of 50Hz mains interference, becomes sizable at larger transmission distances. However it can be filtered out selectively. This mode of communication can be developed for application in home automation and in situations where radio transmission is impossible (eg. inside caves).

Sam Blackman, Richard Cowley

THE GUT(TER)S OF IT

BAY OF PLENTY

ROTORUA BOYS' HIGH SCHOOL

"Pass me the bucket, Rich!" my older brother, Garrick, yelled. I did as I was told and the bucket flew through the air as if it would take a lifetime to reach the intended target. As Garrick made a small adjustment to his footing, the bucket collided with his head and he fell to the ground with a thump. Garrick was not happy and my punishment was yet to come. After this experience I decided that something was needed to make cleaning the gutters more efficient, easier and safer.

So I got together with Sam and we started to make some prototypes for Gutter Cleaners. First we made really basic cleaners that were used from the roof. They were our tests to find the basic methods of cleaning gutters. We found that brushes and water worked best to loosen debris and that plastic was the best to pick it up with. We found out a lot of little things that would help us to develop our prototype better.

With this information we started to design and plan every concept that we could think of. We thought about movement along the gutter; loosening, picking up and containing debris; and the blockage of downpipes. For each problem we drew up sketches of our ideas and then we tried to combine the ideas together.

We then made prototypes of our ideas. We tested these and found what worked well and what didn't. If something didn't work we would scrap it and if something worked well we would try to improve it. When we knew exactly what the cleaner should be like, we had to make it and then test it again for further improvements.

We have a friend who is a welder, so we asked him to weld together the parts of our prototype. It had pulley wheels with the right contour to run along the gutter. These wheels were on the inside of a steel frame that was curved over the edge of the gutter. We called this contraption the "gutter taxi". Attached to our gutter taxi we had a bottlebrush to loosen debris, a metal fork to also loosen the tough, dry debris and a hose with three water sprayers out the side to help the fork and brush to loosen the debris.

The debris flushed away was sometimes blocking the downpipe so we developed an attachment using mesh netting over the top of the downpipe, collecting debris but letting water flow freely through the attachment to the soak hole.

The downpipe attachment was just a backup for the main scooper that picked up the gunk in the gutter. The main scooper was made of plastic and was attached to the gutter taxi.

Because it would take too much time to bring the scooper down each time we made a "basketball hoop" bag for the debris caught by the scooper.

After six months of trials, idea and development we had made cleaning the gutters more efficient, easier and safer.

Ellen Conner

LIGHT, TEMPERATURE AND CALIFORNIAN POPPY FLOWERS

CANTERBURY/WESTLAND

RICCARTON HIGH SCHOOL

The flowers of Californian poppy (Eschscholzia californica) were observed in our home garden to close at night and when days become cold and dull. This suggests that the opening and closing of the flowers is not a routine response to day length, but is in response to an environmental trigger. Is the flower closure a response to decreased light intensity, or is it due to the drop in temperature as the sun disappears? The aim of this project was to determine if Californian poppy flowers open and close in response to changing temperature and/or light intensity.

A series of experiments were performed that follow on from each other. For consistency it was important to use the same sort of flowers in all of the experiments. The "Milkmaid" cultivar of Californian poppy was chosen because it was available in large numbers.

The first experiment investigated the presence and absence of light combined with cold (4°C) and warm (25°C) temperatures on cut flowers. After overnight exposure to these conditions the flowers were closed in the cold temperature in both light and dark conditions. In contrast, in the warm temperature all of the flowers were opened whether in light or dark. Therefore the opening and closing of the flowers was in response to temperature. The presence or absence of light appeared to have no influence on the opening or closing of the flowers.

The critical temperature, to induce flowers to either open or close was investigated in the second experiment. Cut flowers (closed) were placed in 4°C (in darkness) and the temperature was slowly increased to 35°C over 2.5 hours and then slowly decreased to O°C over 3.5 hours. It was observed that the flowers began opening at 24°C with increasing temperature, but upon decreasing temperature they did not begin closing until 16°C. From these results it can be concluded that the opening and closing may result from a delay in response. Therefore both open and closed flowers were tested at 18°C. The closed flowers opened slightly and the open flowers virtually closed, but both responses took 4 hours to occur.

Cut flowers from at 4°C (fully closed) were transferred to 27°C and cut flowers from 27°C (fully open) were transferred to 4°C. Both flower opening and closure started to occur within 20 minutes. Closure was completed after about 2.5 hours whereas complete opening required 4 hours. This experiment was repeated except that the flowers remained on the plant to see if this would alter the response time. The flowers had fully responded after 2 hours, which means the flower opening response time is quicker when flowers remain on the plant.

The overall conclusion form this project is that Californian poppy flowers open and close in response to temperature and not to light.

Georgia Piggot

BLOOMIN' BULBS

CENTRAL NORTHLAND

WHANGAREI GIRLS HIGH SCHOOL

I have been entering the Genesis Energy Central Northland Science & Technology Fair for seven years and I wanted to do something that was interesting for me, so I chose to do a project on calla lilies. I have grown up with them because my family exports them and I used to grow them and sell them for pocket money. I knew a lot about this topic and wanted to do an investigation that would be of great value to commercial growers. I found that autumn flowering was a little investigated topic and if done properly could provide many rewards for growers.

Optimising flowering of calla lily was the goal I successfully achieved in conducting my investigation. I chose to investigate different methods of senescing calla lily tubers at the end of their flowering season to give optimum results in an autumn flowering season.

Calla lilies are a commercially produced cut flower which naturally grow on an annual cycle where they naturally flower in summer and senesce in autumn. The commercial grower then lifts the tubers and prepares them for replanting the next spring. Plants can be artificially senesced, and tuber lifting can be completed by February, thus providing an opportunity to grow an autumn flowering crop.

I chose my topic because I have grown up around calla lillies, as my family exports them, and so it was a project that interested me. It helped having good background knowledge of my topic before I started this investigation. It is also an area that has not been widely investigated by anyone and is of importance to commercial calla lily growers.

I used several different methods of treating the plants for my experiment. The first was to lift the plants in mid May from their natural environment (growing outside), and senescing them inside a polyhouse in dry conditions. This was treated as a control. The other six treatments were different commercially viable options. All plants were growing in the polyhouse. I varied the dates the plants were lifted (the usual mid May and later lifting in late June), and the different conditions the plants could be exposed to when senescing (dry, sunny conditions inside the polyhouse, wet conditions outside and cool, dark conditions in a bulb storage shed). The plants were left to senesce until late February when all the leaves and roots were removed, the tubers were weighed, treated and planted into polystyrene grow boxes.

The plants were then grown in the polyhouse, watered when necessary and the number of flowers produced and size of plants was recorded. When the autumn flowering season finished the resulting plants were lifted, senesced, re-weighed and the number of new, resulting tubers were counted.

After analysing my results I came to several conclusions. The tubers lifted at the latest possible time (in June) gave the only commercially adequate amount of flowering (at least one flower per tuber). The process used to senesce had a smaller effect than the time at which the plants were lifted. I found the best method of senescing was to dry the plants in the polyhouse.

The implications of my findings were that the current timing of growing calla lilies in the autumn is not adequate to be used commercially. Having a longer length of time before lifting the plants out of the ground had a huge impact on the subsequent flowering, and is necessary for growers to produce a successful autumn crop.

Mark Galloway

TOOTHBRUSH TROUBLE

CENTRAL SOUTH ISLAND

ASHBURTON COLLEGE

My topic came about because it was observed that toothbrushes are used day after day, even after people have colds or other illnesses. They are left in or on bathroom cabinets and picked up again at any time to clean teeth. What ever happens to be on the toothbrush is reintroduced into the mouth at the next brushing. Toothbrushes seem to be very unhealthy everyday objects, even though they are changed from time to time.

My experiments looked into the amount of bacteria remaining on a toothbrush after brushing and tested the effectiveness of five disinfectants. The experiments aimed to establish whether there was a significant amount of bacteria remaining on a toothbrush after brushing and, if so, what was an effective way of disinfecting the toothbrush overnight.

In the first experiment a new toothbrush was tested for bacteria. It was established that there were no bacteria on the toothbrush.

In the second experiment a new toothbrush was used to brush the teeth. The toothbrush was left in its usual place overnight, a toothbrush holder in the bathroom. The next day the toothbrush was swabbed and any bacteria transferred to blood agar to culture. It was established that a significant amount of bacteria remained on the toothbrush when it was left in its usual place overnight.

The third experiment aimed to establish whether toothbrushes soaked in one of five disinfecting solutions would decrease the amount of bacteria remaining on the toothbrushes. Five toothbrushes were used to brush the teeth. The toothbrushes were then placed in disinfecting solutions overnight. The toothbrushes were swabbed the next day and any bacteria transferred to blood agar to culture the bacteria.

The solutions chosen to disinfect the toothbrushes were:

Milton, a hospital grade disinfectant used to sterilize baby's bottles and teats
Household Bleach, or hyperchloride, as suggested by dentist
Iodine as suggested by pharmacist
Hydrogen peroxide solution, Iodine solution (H²0₂), which can be used as a short term disinfectant
Boiling Water

My overnight results showed that bacterial growth was inhibited by the use of these disinfecting solutions, although in no instance was the solution totally effective in eradicating bacteria. The most effective disinfecting solution was household bleach as recommended by the dentist.

The fourth experiment was a repetition of experiment 3 for one week, to establish whether the results were conclusive over time. The results were similar to that of experiment 3.

I concluded that if disinfecting a toothbrush was an option, bleach would be the most effective disinfecting solution.

Chris Brake

MASTER THE DISASTER

CENTRAL SOUTH ISLAND

ASHBURTON BOROUGH SCHOOL

Although we describe floods as disasters, they are in fact natural phenomena. Floods can be helpful to the environment by making the land fertile, but equally in some circumstances may be disastrous. To minimize the effects of a flood, especially around inhabited areas, stop-banks are built to constrict or redirect the overflow of rivers.

Floods often occur with little warning and sandbagging is often the only temporary measure available to minimize flood damage. My project set out to discover what type of readily available materials would make the best fill for sandbags to combat floodwaters. To do this, I made up miniature sandbags of two types of material - hessian and plastic, and tested six different types of fill in each type of bag.

Fills used were sand, sawdust, fine gravel, coarse gravel, wool and soil.

I made a flood plain by getting a flat piece of wood to which I attached sides and a runoff collection area at one end. A piece of wood was placed underneath the floodplain to give it a slight incline. A container was placed at the bottom end of the plain to measure the amount of water that escaped the sandbags. The sandbags were placed about halfway down the floodplain in two staggered rows. I then ran a simulated flood by pouring two litres of water at the top end of the flood plain. I measured how much water had escaped the sandbags after forty seconds. I did this three times for each type of sandbag material and each type of sandbag fill.

My hypothesis was, the more dense the material, the better it would be as a sandbag fill and this proved to be the case with sand, fine gravel and sawdust being the best type of fill to use. Most tests showed, the wetter the filling, the less effective it became. Sawdust proved to be the exception with the results showing the wetter the sawdust, the better the restriction of water, possibly indicating that sawdust becomes denser when wet, and therefore this was consistent with my hypothesis.

The results showed hessian to be the best sandbag material for the following materials - sand, fine gravel and soil. Plastic was the better sandbag material for wool, sawdust and coarse gravel. Wool was clearly the least effective filling and I would not recommend it for use in sandbags.

Hessian bags had the advantage that they were easier to stack than plastic bags, and hessian is biodegradable, therefore more environmentally friendly. This is important, as often sandbags are washed away in floods and not retrieved.

Overall, my recommendation was to use hessian bags with either sand, fine gravel or sawdust.

Linda Moore

STREAM MATTERS

EAST WAIKATO

MORRINSVILLE COLLEGE

The Waikato Region has more than 16,000 km of rivers and streams, all of which have changed dramatically since European settlement. They have been dammed, had water pumped out or diverted, waste discharged into them, and exotic plants and animals introduced. The land draining into these rivers has been cleared for agriculture, forestry and urban development. These activities have all increased the amount of runoff entering rivers and streams. This is why it so important that the natural freshwater resources are managed well.

The aim of my project was to investigate the effects of one small dairy farm and the surrounding environment on the stream system flowing through it.

Particular planning was needed to prepare a stream monitoring programme. A map was drawn locating streams, buildings, drainage outlets, and any other physical factors likely to contribute to the stream or drainage systems. From this map, monitoring sites were selected, located, and checked for accessibility. Time of monitoring was determined, a monitoring form made to record stream habitat information, and monitoring was then carried out every second day over the period of a month.

The first part of my investigation involved measuring stream habitat and taking samples at Site 1, the input site (entering the farm), at Site 2 , the output site (leaving the farm), as well as a single reference site along the main Paranui stream. This enabled me to observe and calculate the effects of our dairy farm on the old Paranui drain flowing into the main Paranui stream. This stream is within the Managawara river scheme and ends at the Waikato river.

The stream monitoring programme involved the use of NIWA’s Stream Health Monitoring and Assessment kit. This was used to record stream habitat measurements of the following:

water pH
water temperature
water conductivity
water clarity
measuring rainfall
observing composition of the stream bed, deposits and bank vegetation
assessing Stream bed life

Measurements were grouped into rainfall affected measurements and non-rainfall affected measurements.

The second part of my investigation involved the Analysis of suspended and volatile solids at each of the three sites on both rainfall affected and non-rainfall affected monitoring days.

Results were collated, analysed and statistical data produced.

A brief overview of my results is as follows:

The average pH readings for each site did not differ greatly between non-rainfall affected sites and rainfall affected sites
The average temperature reading for each of the non-rainfall affected sites was lower than the average temperature reading for rainfall affected sites
The conductivity was not affected much by rainfall. The conductivity at site 1 was always lower than the conductivity reading at site 2.
Water clarity was greatly reduced by rainfall.
There is a negative relationship between total suspended solids and water clarity. When total suspended solids increases water clarity decreases.
There is an obvious increase in inorganic solids between site 1 and site 2. The increase in organic solids between site 1 and site 2 is not very great.
Biological data was recorded and assessed at each of the three sites and scored accordingly.

This has been a hugely interesting investigation looking closely at the affects of a dairy farm and the surrounding environment on the stream system passing through it.

This study is just one part of my Gold Crest Project. I intend to carry out further investigations into the habitat quality of the Mangawara stream system and attempt to measure the significance of what the surrounding environment contributes to the stream system.

Joshua Drummond

POISON SAFE

FAR NORTH

KERIKERI HIGH SCHOOL

They say "necessity is the mother of invention". My research is all about that concept.

The problem? Pets, especially cats, find the taste of ant poison sweet. My house has had a bad ant problem, and we own two cats and a dog.

I wanted to design and build an ant poison dispenser that pets cannot get into. I developed the original concept from a tin lid. I made the first mock-up out of balsa wood, using a razor blade and PVA glue. The first working model I made out laminated acrylic. I glued several sheets of acrylic together with superglue and carved the final shape out on a lathe.

I tested the design by simply filling the dispenser with poison and doing a count of ant numbers. I also worked out a testing method of seeing whether or not pets could get into the dispenser.

The overall results from the testing were good. Now I am working on designing a future child-proof model of the dispenser. I believe that the PoisonSafe product has a definite future in the marketplace, being both effective and practical. I have spoken to a number of possible future developers for PoisonSafe and I'm looking at perhaps patenting the product.

Work is still underway on the concept itself - designing, redesigning, looking at other applications, etc. The design and technology process is always in the background - that of constantly refining the product.

In an age of Information Technology dominated products and systems, PoisonSafe is proof there is still room for the KISS (keep it simple, stupid) principle in simple, effective and practical designs as solutions to everyday problems.

Amanda Maclean

"EYE TIME"

GISBORNE

GISBORNE GIRLS' HIGH SCHOOL

The aim of this project was to find whether the iris of the eye reacts at different speeds in different light frequencies, and if so, how.

The experiments test a wide range of people, and the reaction times of their iris's, by shining light through different coloured filters into their eyes. The results are filmed on a video camera so the times can be measured and recorded.

The general trend of the results shows the reaction time of the iris increasing as the frequency of light increases. That is, the iris responds more quickly in red, more slowly in violet light.

How can these results be explained? Assuming that the brightness of the different colours was effectively the same, then the result cannot be explained in terms of energy levels as I had first expected. Instead the time to react relies on the reflex nervous system of the eye which is tuned to react in a special way to different wavelengths of light. My results suggest that longer wavelengths (the red end of the spectrum) achieved a quicker response from the iris.

Could this have something to do with the association of red with danger? It could be that the nervous system as a whole is more sensitive to this colour, and the eye reaction is just part of a larger pattern.

Alternatively, the explanation could be that red contrasts with the more relaxing green and blue colours of the world we evolved in, which our eyes are used to.

An interesting extension would be to compare reaction times for subjects of different sex, age, race, and states of health with each other.

Roseanne Coulter

SECRETS OF SADDLE ROAD

MANAWATU

PALMERSTON NORTH GIRLS' HIGH SCHOOL

This project aimed to geologically map an area and then provide a paleoecological interpretation (reconstruct the environment). The mapping was done in an area defined on the south by the Saddle Road (which straddles the Tararua/Ruahini Ranges) and the west by the Pohongana River over a period of two years (1999-2000).

The reason for doing this investigation started out purely as curiosity and enjoyment. The area I mapped is very small on the scale of things and of little use in the location of usable minerals etc. However, as my understanding of geology and its applications grew so did my ability to relate what I was observing to the 'real world'.

A quarry was opened at the top of the Saddle Road to supply gravel for road use. Lately it had been cheaper to take gravel out of the Manawatu River, but the permit to use gravel extracted from the river ends soon - so a new source of gravel must be found. Finding the extent of useable gravels in the saddle road area might help in determining an alternative source.
Gaining an understanding of the rocks in the Saddle may provide a small piece of the puzzle that explains the present geography of New Zealand. As the sedimentary layers are particularly well preserved, (successive layers did not completely erode pervious beds) the sequence of rocks is like a control for the Manawatu/Wanganui region over the last three million years.

During a number of field days approximately fifty exposures were sampled and topographical and geological maps were built up. Samples of fossils and rock types were taken. Fossils are a key way of dating rocks and give insight into environmental conditions at the time they were living - so their identification was important. After finding the world of mollusca fossils a little beyond my pronunciation, I sought help from a specialist. In a short three to four hours, I had over a hundred and twenty species named. From this information I was now able to give approximate dates to the strata, and when combined with other information gathered from the location (grain size, colour etc) I was able to determine likely environments.

I concluded that there are eight main strata, although some are a collection of possibly very thin strata (some only a few metres thick) as opposed to the bands or lenses they have been called. The oldest rock type is a blue/grey marine mudstone which is approximately two and a half million years old.

The environments which the different sediments were laid down in vary from; deep marine (oldest), alluvial or river, marine, beach/shallow marine, beach, marine/estuarine and coastal (youngest). The three million years the Saddle records covers only moments or two in geological time, but as geology goes it was a busy moment.

Blazej Kot

CALCULOGGER

MANUKAU

MACLEANS COLLEGE

A datalogger is a device that collects data from the environment and records it for further analysis. Dataloggers are often used by environmental engineers to record data such as temperature and humidity (for example, in weather stations).

Many dataloggers are not self-contained; this means that they need to be connected to a computer to record data. However, this reduces their portability and cost. Self contained dataloggers also exist, but they are expensive.

I saw a need for a new type of datalogger - a self contained, portable and inexpensive model. Ideally, it should also be able to carry out statistical analysis on the data collected by itself, completely eliminating the need for a computer.

I decided to use a CASIO graphical calculator to provide the statistical analysis capacity of my datalogger, the memory to sort the data and the display to present it.

The calculator I used has a special port for communicating with a computer. This meant that in principle my idea could work. I would be able to make a 'black box' that plugged into my calculator at one end, and accepted data from sensors at the other - a CalcuLogger.

I tried to find out whether a similar device had ever been created before. I only found once such device - a CASIO datalogger. However, this is an expensive, self contained datalogger which costs NZ$300.

My task was set: to create an inexpensive device that accepts real-world (analogue) data from various sensors and transmits them to the calculator.

The first challenge was determining how to transmit data to the calculator. I "only" needed to figure out how, volt for volt, bit for bit, the calculator communicates. Neither CASIO nor any other sources on the Internet provide any information about this. Eventually, after a lot of work, I managed to crack the code.

Next, I used a PIC and an ADC to create my CalcuLogger. A PIC is a single-chip computer that costs about $15. Just like a big computer, it has to be programmed to do anything useful. An ADC is a single-chip circuit that can convert analogue signals from sensors into digital data. I designed a circuit for the PIC and ADC and constructed it. I then wrote a program for the PIC to control the ADC and to communicate with the calculator.

This was a difficult time consuming task, but I finally got the CalcuLogger working. I tested it by carrying out a simple experiment, which is passed with flying clours.

As it stands, the CalcuLogger costs about $70 to make. However, this cost could be reduced if it were mass manufactured. Its size is currently similar to that of the calculator, but it could be brought down to as little as two or three matchboxes. The CalcuLogger can sample up to 11 different sensors of 0 - 5V with an accuracy of 0.02V.

The CalcuLogger has significant potential for applications in both the environmental sciences and in education. This simple, inexpensive and reliable device would be a great addition to any environmental engineer's equipment and to any school's science department.

Ben Paterson, Ellen Paterson

"PARA PLAY"

MANUKAU

MACLEANS COLLEGE

We set out to design and construct a piece of playground equipment as an addition to family restaurant playgrounds that can be used by both able bodied and disabled children. To do this we needed to brainstorm several ideas and come up with some conceptual drawings of playground equipment. With six of these concept designs drawn we analysed the positive and negatives keeping in mind factors such as safety, maintenance and play value. As a result of this process we reduced our choices to 2 concepts;

A board that moves on a pivot
A merry go round

By weighing up the positive and negatives of each we chose the board that pivots, or as we nicknamed it, a "Wobbly Board" (We later discovered during our research that merry-go-rounds are no longer deemed safe as a play activity by Standards New Zealand).

We conducted research into playground standards, wheelchair measurements, the different types of immobilisation disabilities and the demographics in Auckland and New Zealand of children with disabilities. This gave us an indication of the demand for disabled playgrounds especially in restaurants and how marketable it would be.

From our initial concept of a wobbly board with a fixed pivot we developed it to a board resting on numerous fixed ball bearings with springs attached to an outer frame. We refined our design to incorporate the required safety elements.

With the design part out of the way we began to concentrate on the construction side of the project. Firstly we sourced the materials we required for the wobbly board to be made and began construction. The first step in construction was to set out the base for the wobbly board and the frame that circles it. We nailed the framing together and screwed in the hooks, which were strategically placed to hold the shock cord (a springy rope as springs were too expensive). We then constructed the base out of construction ply, glued a large sheet of stainless steel on and bolted this to the framework. With this finished we constructed a kick-board and handrail to go around the outside of the board (this was for safety reasons). We then screwed the ball bearings on to the bottom of the board in strategic positions and calculated how many would be required to hold the desired weight. We constructed a ramp so that the disabled person could get onto the board and then we painted it.

After several weeks of hard labour the wobbly board was finally complete. We reassessed our piece of playground equipment and conducted several tests including ease of use, safety and shock cord stretch which would help us find out how much force was required to move the board.

A marketing plan was then developed to enable the wobbly board to be put on the market. The wobbly board was trialed by a disabled adult, and a child in a wheelchair as well as able-bodied children.

From testing our apparatus with both physically-abled and paraplegic people we have been able to conclude that it is possible to design and construct a fun safe piece of playground equipment which may be used by both able-bodied and disabled children. During our testing programme we found that the apparatus we designed may also have additional benefits in the exercising and rehabilitation of disabled people.

Katie Ayers

THE BEHAVIOUR OF FLATWORMS

NELSON

NAYLAND COLLEGE

I chose to study flatworms because as a child I was very interested in them and I used to find them on my beach house in the sounds.

Flatworms are a very primitive animal with very simple behaviour and it was this behaviour I wanted to study.

The flatworm Leploplana lives in abundance at the Monaco mudflats, so this was the species that I studied.

After observing some flatworms, I noticed that they would not stay on top of rocks if placed on it, but instead they would crawl underneath.

The questions I asked myself were:

Do they travel under the rock to avoid light (negative phototaxis), because they are positively geotaxic (travel towards gravity), or is it because of both responses. If it is because of both responses which of the two is the strongest response in the flatworm behaviour.

With the use of a suspended ball, a box to separate the ball into halves, and a light, I set out to investigate the flatworm’s phototaxic and geotaxic responses.

I discovered that my original hypothesis was proved, but also that both senses were responsive to some extent.

Karen Brooks

SPIDER OF THE NIGHT

NORTH HARBOUR

HIBISCUS COAST INTERMEDIATE SCHOOL

At the beginning of the year I found an unusual looking spider in my garden. It turned out to be a two-spined spider, (Poecilopachys australasiae), a recent immigrant from Australia. The spider is quite special as it spins its web at night and eats the web and any catch in it before dawn. Not much more is known about the spider.

I decided to observe the spider and see what it caught and any other interesting things it did. I was careful not to interfere with the spider and watched it daily, just before bedtime and in the early hours of the morning between 3.00am and 6.00am. Within a fortnight I had discovered another three two-spined spiders in my garden.

I was interested in seeing what the spiders caught, as it was thought they only caught the male leafroller moth. Unfortunately the spider wrapped up any leafroller moth immediately and I could not identify the gender. I did not unravel the wrapped moth as the spiders did not catch many moths and I did not want to interfere. The spiders also caught another type of moth that was much smaller but I never saw this moth being eaten.

However I did observe some interesting things about the spiders. They lived in, or very near to a citrus tree. These trees were all on the sheltered side of our section and infected with leafroller.

I observed four different types of webs. These webs seemed to be dependent on the weather. On very windy nights the spider spun no web at all and went hungry. On very still nights the spider would spin an orb web ranging from 0.5 to 1.5 metres wide. On other nights the spider made a "ladder" web or a "line" web. Some of the webs had long lines dangling from them with sticky blobs at the end. Moths were caught in these blobs. A lot of the time no moths were found in the webs.

Sometimes the spider started making a web in the daytime. This was a web around a group of leaves in preparation for an egg sac. The spider spent three days working on this before it laid a large white egg that it wrapped in gooey clear liquid that it pumped from its bottom. The liquid dried to a light brown and made a sac around the egg. The spider did not spin a "night" web during this time and so went without food. One spider made a second egg sac only 15 days after completing its first sac.

By the end of the first week in April, two of the spiders had died and the other two had disappeared. I think it was because of the cold weather.

I now check the citrus trees and garden regularly in the hope that I may find some more two-spined spiders to continue my observations. Perhaps I will be lucky if they return this summer.