Watch carefully. A little water lands on the bench. Which cloth will soak up more: the paper towel or the tea towel?
How could we find that out fairly, so the comparison is honest?
Our question: Which material soaks up the most water?
Look at the materials we will test. Whisper to your partner which one you think will hold the most water, and say why. Predictions are the start of the science, not a guess to get right.
We'll sort five cards on the board together: the material, how much water it holds, amount of water offered, size of each piece, time it sits. Call out whether each one is Change, Measure, or Keep the same.
As we place them: a fair test changes only one thing and measures one result; absorbency is how much liquid a material soaks up; an average is a sensible figure from more than one reading.
Then complete your Investigation Journal page for our question: which material soaks up the most water?
Which material soaks up the most water?
Watch how we measure ml held. Do not write on your journal yet — that starts when your group tests.
Our class method (everyone will use this):
- Each piece is the same size (about 10 cm square).
- Offer exactly 10 ml of water from the syringe.
- Wait 30 seconds (same time for everyone).
- Gently tip the tray so free water gathers in one corner, draw it back into the same marked syringe, and read ml free.
- ml held = 10 − ml free.
We will do each material twice with a fresh dry piece each time, then find the average.
In your group, test the materials one at a time using the class method on the board. Write each reading on your Investigation Journal page as soon as you measure it — only your group's own trials.
Method every time: same-size dry piece → offer 10 ml → wait 30 seconds → tip the tray so free water gathers, draw it into the syringe, read ml free → ml held = 10 − ml free.
Do each material twice with a fresh dry piece each time, then work out the average. We compare how much each piece holds in 30 seconds, same time for everyone.
If time is tight, finish two materials fully (two dry trials and averages each) and we will pool class data, or cut the set to three materials. Keep the method identical so only the material changes.
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