Glow Stick CER Exemplar
8th Grade Physical Science MS-PS1-2
Glow Stick CER Exemplar
Student Guide: Physical vs. Chemical Changes
Name: __________________
Date: ________
Class Period: ____
Guiding Question
Is snapping and activating a glow stick a physical change, a chemical change, or both?
Model Student Writing
Clear & Direct Middle School Language
1. Claim Your direct answer
1 Sentence
Snapping a glow stick is both a physical change and a chemical change.
2. Evidence What you actually see, hear, or feel
Observations
First, when you bend the plastic stick, you hear and feel a small glass tube snap inside. Second, after the glass breaks, two liquids flow together and mix. Third, as soon as the liquids mix, the stick glows with bright neon light.
3. Reasoning How the science rules explain your evidence
Science Rules
A physical change changes the shape or size of an object, but it does not make a new substance. Snapping the small glass tube is a physical change because broken glass is still just glass. A chemical change happens when substances react to create brand-new substances with new properties. Releasing light energy is clear proof of a chemical change. When the two liquids mix, they react and produce light. Because the glass physically breaks and the liquids chemically react to make light, activating a glow stick includes both types of changes.
Why This Response Works: Quick Checklist
Claim
- Answers the question directly.
- No "I think" or "maybe".
- States both changes clearly.
Evidence
- Only lists what happened.
- Mentions the glass snapping.
- Notes the bright light.
Reasoning
- Defines both terms simply.
- Explains why broken glass is physical.
- Explains why light means chemical.
Key Science Vocabulary
Physical Change: The material changes shape or look, but stays the same thing.
Chemical Change: A reaction happens and makes something brand new.
Helpful Writing Tip
In your Evidence, only share what you saw or heard. In your Reasoning, use the word "because" to connect the evidence to the science rules!
