A good science warm-up starts with something that makes students ask "wait, why does that happen?" A phenomenon does that better than a vocabulary review. Show something real, ask students to explain it with what they know right now, and you'll learn more about their thinking than a quiz would tell you.
What counts as a phenomenon
It doesn't need to be dramatic. Condensation on a cold can. A balloon that shrinks in the freezer. A photo of a river that splits into a delta. Ice that floats while most solids sink. The best ones connect to the unit you're about to teach and have an explanation students can reach in a few days.
The three-question routine
Keep the prompt the same every day so students know the drill:
What do you notice?
What do you think is causing it?
What would you need to know to be sure?
The third question is the most important. It pushes students past guessing and toward thinking like scientists, and it gives you a list of the questions your lesson needs to answer.
Use photos and short clips
A single photo projected on the board is enough. A 20-second clip works too, but keep it short so the warm-up doesn't turn into a video day. Play it twice, then have students write. Ask two or three students to share, and write their explanations on the board without judging them yet.
Return to it at the end of the unit
Save the students' first explanations. When the unit wraps up, show the same phenomenon again and have them explain it a second time. Putting the two side by side is one of the clearest ways for students to see their own growth, and it makes a strong exit ticket. The science exit tickets guide has formats that work well for this.
Catch misconceptions early
Phenomena warm-ups surface misconceptions on day one. If half the class says the water on a cold can leaked through the metal, you know what to address. The formative assessment strategies in science article on Elevate the Norm covers more ways to find and fix those early.
Keep going
Need something ready to use tomorrow? The Teacher Emergency Toolkit has grab-and-go packs for de-escalation, work refusal, behavior documentation, and sub plans.