Sort adult observation records and explain when a material returns to its starting state.
What it is about
Distinguish reversible examples from changes that cannot be reversed by cooling.
Grade 2 · 7–8 years · 30 challenges
Before you begin
Grade1 structure/function, observations and evidence-based design.
What the class will do
Sort into groups · 10 challenges
Compare the observed changes
Read the supplied adult records. Compare the starting and final material states; do not perform heating experiments.
Choose and explain · 20 challenges
Explain a return or non-return
Predict and discuss together. Choose the claim supported by this challenge’s own before-and-after evidence.
Using it in class
Everyone compares the starting and final records before a rotating representative acts. Optional narration supports reading. Use these supplied observations; no heating, tasting or handling hot materials. Plan 30–45 minutes for all 30 or choose a short round.
Give everyone time to think and discuss before one pupil acts at the board. The class explains and confirms together; hints and explanations stay until you move on.
Use an up-to-date browser on a computer connected to a whiteboard or shared display. Touch, mouse and keyboard; optional audio and reduced motion. No pupil accounts or personal devices.
Choose from 5 challenges up to the full activity. Discussion determines the duration: you set the pace.
A look inside the activities
Sort into groups
These are adult observation records. Did cooling return the material to its starting state?
Egg: cooked; cooled but still cooked
Ice: melted; cooled until solid ice again
Butter: melted; cooled until solid again
Groups: Returned by cooling · Did not return by cooling
Explanation and discussion
Ice and butter return to a solid state in these records. The cooked egg stays cooked after cooling. Becoming cool is not the same as undoing a change.
What must a return record include besides temperature?
Choose and explain
An adult record says: raw egg → cooked egg → cooled cooked egg. Which conclusion fits?
The egg returned to raw because it cooled
Cooling did not make the egg raw again
Every heated material must behave like this egg
Explanation and discussion
The egg remains cooked after cooling. The record supports a non-return for this example, without claiming that all heating changes behave alike.
What would count as evidence of a return to the starting material?
Sort by properties
Parts can be rearranged
Choose a suitable material