Good Science Victorian Curriculum Year 7

INVESTIGATIONS
Investigation 3.2
Modelling a pond ecosystem
KEY SKILL
IDENTIFYING LIMITATIONS TO THE METHOD
AND SUGGESTING IMPROVEMENTS
When you write a formal investigation report there is
always a discussion section that includes a discussion
of potential errors. These errors are limitations
(or problems) with the method. For each error, you list
a way to control it (your suggested improvement).
Hint #1: Brainstorm three potential errors that might have
occurred in this investigation that could have affected or
changed the results you collected (for example, if through
human error something was not measured accurately).
Now work with a partner to suggest ways each error could
be controlled.
AIM
To investigate a pond ecosystem using a model
30 min
6 Every few days for 2 weeks, make observations about
your ecosystem and re-weigh the jar to record the
mass. Record your observations.
7 Draw a diagram of your model ecosystem.
QUESTIONS
1 What changes did you observe in your ecosystem
over the 2 weeks?
2 Where do the different organisms gain their energy
to survive in the jar?
3 Why was there a change in mass? Suggest a reason
for this.
4 Draw one food chain for this ecosystem.
CONCLUSION
Copy and complete:
‘The results show that: (respond to the aim)’.
Level 1
MATERIALS
• clear glass jar with lid
• sand
• pond water containing water fleas, water snails and
microscopic organisms
• Myriophyllum (water weed)
METHOD
1 Add sand to your jar to form a 2–3 cm layer.
2 Slowly fill your glass jar with pond water until it is
almost full. Make sure you have some water fleas and
a snail in your jar.
3 Add 2 or 3 pieces of the plant to your jar.
4 Place the lid on your jar and seal it. Weigh the jar and
record the initial mass in your notebook.
5 Place your jar near a window, but out of direct
sunlight.
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