Hidden fresh water, watersheds and insect clues
Answers are for parents and teachers.
1
A 2000 mL jug stands for all fresh water on Earth. About 70 out of every 100 parts are ice. How many mL stand for ice?
2000 ÷ 100 = 20, and 70 × 20 = 1400 mL.
2
Draw a watershed with two streams that join into a river. Mark where a farm could pollute one stream, and colour the path of the pollution.
The colour follows the polluted stream, then the river and the sea, but not the other stream.
3
Make a table of three insects and the kind of water each one tells you about.
For example: mayfly nymph, very clean; dragonfly nymph, a little pollution; midge larva, poorer water.
4
Creek 1 has 8 clean-water insects and 2 poor-water insects. How many insects is that in all, and how many more clean-water ones are there?
8 + 2 = 10 insects in all. 8 − 2 = 6 more clean-water insects.
5
Write a claim, evidence and reasoning for: Why is fresh water precious?
Claim: fresh water is precious. Evidence: only about 1 part in 100 of it is easy to reach. Reasoning: living things need it and it is hard to replace, so we must use it wisely.