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Fresh water activities

Use our fresh water activities to learn more about streams and wetlands in the Waikato region.

Students investigating the water treatment process.

Bug food and stick races

Stream insects (and other aquatic invertebrates) feed from materials within the stream:

  • Algae growing on rocks are munched by grazers e.g. snail.
  • Fragments of organic matter are netted by filterers e.g. sandfly larva.
  • Leaves and twigs that become trapped in the stream are dismembered in a leisurely fashion by browsers and shredders e.g. mayfly.
  • Predators prowl trying to capitalise on the hard work of the grazers, filterers, shredders and browsers (i.e. eat them!) e.g. the glamorous toebiter.

The stream ecosystem benefits from organic matter (leaves, twigs etc.). Without it many bugs (and bug-eating bugs) would not be able to survive. No takeaways - no bugs!

What is your stream like for contributing leaves, twigs etc. and for retaining this material? A stick race should help you find out.


  1. Select a safe section of stream that suits your investigation.
  2. Measure the length of the section of stream you are going to use for your stick race (20m or more is ideal).
  3. Collect sticks of suitable size (30cm x 1cm). Note the availability of sticks and leaves near the stream (i.e. sources of organic matter).
  4. Place your sticks at equal intervals across the stream at the starting line.
  5. Release the sticks and follow their progress. Watch how they move and what they get caught on.
  6. Record the distances each stick travels and what they get stuck on (long term) if they get trapped.
  7. A winner - from the bug’s perspective - would be the stick that gets trapped first!
  8. This investigation could be repeated using leaves instead of sticks and/or with twiggy sticks. At least 10 sticks/leaves/twigs should be raced to allow a reasonable results.
  9. Enter your results into a table.


  1. How did the leaves travel (compared to the sticks)?
  2. Which mathematical value (mean/median) gives the best idea of what actually happens?
  3. How well does the stream retain organic matter?
  4. How did twiggy branches compare to unbranched sticks?
  5. If you wished to win the stick race (and not feed some bugs!) where would you place your stick in the stream and why?
  6. Is there a good source of organic matter inputs (trees, shrubs) near the stream?

Stream flow

Stream flow rate can be highly variable and is significant for the functioning of the stream environment. Flood flows can cause erosion and sweep away bottom-dwelling stream creatures.

Low flows are usually poorly oxygenated or rapidly overheat if meandering through open areas (bugs draw the line at 25°C or thereabouts).

Flow rates can be determined quite accurately using very simple equipment - an orange (or any other citrus fruit), tape measure and a stopwatch.


  1. Choose a section of stream that is fairly straight and free of snags.
  2. Use a tape to measure out 10m of the stream.
  3. Two people are upstream, one is downstream and the fourth is recording the results.
  4. One person releases the orange into the stream approximately 2m upstream from the person with the stopwatch.
  5. As the orange floats past the timer, start the stopwatch.
  6. When the orange floats past the person who is 10m downstream, the timer stops the stopwatch.
  7. Record the times in a table.
  8. Repeat two more times and then calculate average speed using the formula below.
Average speed of stream = Distance÷Time
  = 10m÷Time
  = _______ m/s


Social Studies

The Place and Environment strand looks at why particular places are important to people and their interaction with that place.

At the higher levels students could look at the importance of wetlands to the water cycle such as flood storage, and sustainable land management practices such as peat bog wetland development.

At the primary level they could explore the immediate effects of people in or near these wetlands, for example farming practices and what we can do to restore wetlands and their endangered species.

Technology curriculum

TheTechnology curriculum offers all sorts of opportunities, especially in the design strand, Technological Capability.

Students could:

  • design and make nesting boxes to keep our native birds safe such as a floating island that can be set up in lakes so there is a water barrier to deter pests
  • design and make specialist traps to assist pest control
  • investigate the properties of our native plants that make them perfectly adapted for the wetland environment and then create their own “perfect plant”.

Students need to be shown why these areas are ofcultural and ecological importance. We need to ensure these valuable resources are not lost forever.

Problem solving - erosion and streams

Two students are wondering whether the speed of water in a stream affects the size and number of rocks it transports. To investigate this they plan the following experiment.

  1. Collect a large jar and two-thirds fill it with water. Add handful of mixed rock fragments to the jar.
  2. Shake and swirl the jar for a few seconds, then stop swirling and watch the contents carefully.

Your job is to complete the investigation and find the answer to the following questions:

  • What happens to the rock fragments as the water slows down?
  • Which fragments (large or small) drop to the bottom first?
  • Which fragments drop only very slowly?
  • Which carries the largest fragments - slow moving water or fast moving water?
  • Decide whether slow flowing or fast flowing streams carry more rocks?
  • Which will be deposited first when a stream slows down - the largest or smallest fragments?

How water flows

How water flows is a water activity from our Rivers and Us unit.

Students investigate how water flows through a catchment.

You can read and print a copy of the How water flows activity off this web site by opening the PDF file below.

How water flows activity
(1 kb, 1 seconds to download, 56k modem)

Muddy waters

Muddy Waters is an activity from our Rivers and Us unit.

Students investigate how water carries soil and chemicals from one part of a catchment to another.

You can read and print a copy of the Muddy waters activity off this web site by opening the PDF file below.

Muddy waters activity
(7 kb, 1 seconds to download, 56k modem)

Taken from Science Works Book 3 by Geoff Watson, Oxford University Press, 1996.