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Science · Stage 6

Investigate: Reversible and Irreversible Changes

Measure it again and again, find the fair average, then let your data tell you what really happened — investigate reversible and irreversible changes like a real scientist!

✦ Science📘 Stage 6 · S6⏱ ~12 min🧒 Ages 10–12★ Free to start
I can take repeated measurements, find the average, and draw a conclusion my data supports.
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Kavi the owl for Science
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Kavi's Fizz Lab

Kavi tips baking soda into vinegar and — FIZZ! 🫧 A new gas bubbles up and will not go back. "Whoa — that change is irreversible; it made something new!" hoots Kavi. Then Kavi stirs salt into water until it vanishes, leaves the cup on the sill, and the next day the water has dried to leave the salt behind. "That one I can reverse!" To be sure, Kavi does not trust one reading — "I measure three times, find the average — the fair middle — and only then say what my data shows. That is how a real scientist draws a conclusion. Let's measure!"

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What your child will learn

1Measure, average, concludeA careful scientist never trusts one reading. Tap each move to see how they turn messy readings into a conclusion you can trust.
2Can you get it back?A reversible change can be undone — nothing new is made. An irreversible change makes a new substance (often with fizz, a new colour, or heat) and cannot be undone. Sort each one!
3Three readings, one fair middleKavi counted the gas bubbles three times. Add the readings — 8 + 10 + 9 = 27 — then share them evenly: 27 ÷ 3 = 9. See how the Average bar sits in the fair middle of the three tries?
4Measure it like a scientistDecide like a real investigator. Predict each one, then tap Next test → for more!
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A peek inside

I counted the gas bubbles three times and got 5, 6 and 7. What is the average?
A fair result uses all my repeats, not just one. I add them: 5 + 6 + 7 = 18. Then I share that evenly between the 3 tries: 18 ÷ 3 = 6.

Try this at home: Why do scientists measure something more than once?

Ready to play and learn?

Start the free interactive lesson, or print the handout for screen-free play.

Start the free lesson →⬇ Download PDF

Part of Science · Stage 6 · S6 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.