Lead with spoken reasoning so students rehearse the "still the same substance" justification aloud.
Narrate the change
At each station, one student is the "commentator" who describes the change out loud as it happens, like a sports commentator: "The ice is melting… it's turning to water… but it's still water, still the same stuff!" Narrating in real time forces attention to what is and isn't changing.
The justification frame
Every classification must be spoken in a fixed frame before it's written: "This is a reversible change because the ___ is still the same and I could get it back by ___." Listen for both halves — the "still the same" and the "get it back".
Call-and-response check
Quick whole-class check: you name a change ("melting butter"), class responds in unison "reversible — same substance!" or pauses if unsure, surfacing disagreement to discuss.