Task
Your teacher will demonstrate several changes to everyday materials. Watch each one carefully and record what you observe. For each change you will decide whether it is reversible or irreversible, say whether a new substance was made, and think about the safety risks.
Results grid
1. Complete the table for each change the teacher demonstrates.
| Material and process | Physical or chemical change? Why? | Is there a new substance? What is it like? | Reversible or irreversible? | A risk and how to reduce it |
|---|---|---|---|---|
| 1 | ||||
| 2 | ||||
| 3 | ||||
| 4 | ||||
| 5 |
Thinking about your results
2. Choose one change you classified as irreversible. Explain how you knew a new substance had been made.
3. Explain the difference between a reversible change and an irreversible change, using an example of each from today.
Rubric criteria (weights as a percentage of this assessment)
| Criterion | Weight | Descriptor |
|---|---|---|
| Classifying reversible and irreversible change | 40% | High (5–6): Correctly classifies every change as reversible or irreversible and provides clear information about any new substance and its properties. Sound (3–4): Correctly classifies most changes and identifies a new substance where one is made. Limited (1–2): Classifies some changes correctly with limited reasoning. |
| Observation and description of changes | 35% | High (5–6): Records detailed, accurate observations for each change and correctly identifies and describes the observable physical or chemical changes that occurred. Sound (3–4): Describes the physical and chemical changes observed. Limited (1–2): Lists a physical change and a chemical change observed, with little detail. |
| Identifying and managing risk | 25% | High (3): Describes safety risks and suggests ways to reduce them. Sound (2): Describes safety risks. Limited (1): Lists some safety risks. |