1. Think about it:
1. What’s the difference between cutting and burning a piece of wood?
2. How should the mass of the products (results of each process) compare to the original piece of wood?

2. Physical and Chemical Changes
AGENDA:
Distinguishing and identifying changes
Steel wool demonstration (this will get started early in the lesson, but we will revisit it several times.
Guided practice to distinguish changes.
Independent practice
And how to tell the difference

3. Physical Change Chemical Change
Substance may seem different, but the way the atoms combine is the same.
Changes the way the atoms combine to form substances
(new substances will have different physical properties)

4. Steel Wool Demonstration
We will be taking observations every 5 minutes for this demonstrations
Teachers: assign a time keeper for the demonstrations and have students assist with recording observations

5. It’s a physical change if
It’s a chemical change if
It’s a physical change if
It changes shape or size
It dissolves.
It changes phase (freezes, boils, evaporates, condenses)
It burns
Temperature changes without heating/cooling
It bubbles (makes a gas)
It changes color
It forms any new materials
How are these different?
Students should distinguish boiling (phase change) from creating of a new gas. Boiling water and the bubbles (carbon dioxide) released from mixing vinegar and baking soda can be used as a reference for students.

6. What kind of change is it if someone...
Tears up paper?
Physical change
Mixes salt and water?
The following examples can be used as think-alouds to model how students should justify answer. Use of individual or group whiteboards or another type of response system can be used to check for understanding.

7. What kind of change is it if someone...
Burns paper?
Chemical change
Evaporates salt water?
Physical change

8. What kind of change is it if someone...
Mixing vinegar and baking soda?
Chemical change

9. Guided Practice (Left Side): For each of the following examples
Decide whether the changes is chemical or physical
Justify your answer.

10. This is the only slide from the guided practice that has a modeled justification. All other examples only state whether to the processes is a physical or chemical change.
Boiling water is a physical change because the liquid water changes state to become water vapor when enough heat is added.

11. Rusting (oxidation)
Chemcal

12. Physical or Chemical Change?
Painting Wood
PHYSICAL

13. Physical or Chemical Change?
Burning Paper
CHEMICAL

14. Physical or Chemical Change?
Digestion of food
CHEMICAL

15. Physical or Chemical Change?
Sugar dissolving in water
PHYSICAL

16. Physical or Chemical Change?
A pond freezing in winter
PHYSICAL

17. Physical or Chemical Change?
Cutting wire
PHYSICAL

18. Law of Conservation of Mass
Matter can never be created or destroyed.
This means:
During any physical or chemical change, the total mass of all substances before and after the change remains the same.
Sometimes, measuring all the components of a change is difficult.
Example: if you boiled water, it would be difficult to measure the mass of all the water vapor.

19. Temperatures influence on chemical changes
As with the steel wool demonstration, adding energy in the form of heat typically speeds up the change.
This means:
During any physical or chemical change, the total mass of all substances before and after the change remains the same.

20. Time (min)
Mass (g)
Color
Other Observations
Room
temp.
Hot
Room temp.