Lesson Plan of Physical and Chemical Changes and Process
General Science Grade VII
Students’ Learning Outcomes
· Differentiate between physical and chemical changes.
· Identify the physical and chemical changes.
Information for Teachers
· There are two kinds of change: physical change/chemical change.
· Physical change: A change in look only that doesn’t make a new substance.
· Chemical change: A change that causes a new substance to be shaped must have at least one indicator.
· A physical change is a change in the size, shape, state, or appearance of matter. No new substances are produced. Example: ice melting to water or water boiling.
· In a chemical change one or more new substances are created. The new substance has different properties from the original one.
· Matter change all the times.
· Physical change: matter keeps the same chemical properties.
· Chemical change: matter change into different kind of matter with different properties.
· A physical change is reversible, a chemical change is not. For example, the freezing of water would be a physical change because it can be reversed, whereas the burning of wood is a chemical change- you can’t ‘unburned’ it.
Material / Resources
Candle, milk, yogurt, salt, baking soda, vinegar, papers
Worm up activity
· Teacher can introduce the lesson by using the following activity:
o Show children milk and yogurt and ask them to explain difference between them.
o Teacher will explain that due to a chemical change milk has changed into a new product with different taste and properties. As it can’t be changed into milk again so it is a chemical change.
o Light up a candle in class. Candle will start to melt.
o Students will be explained that as candle wax has melted due to heating. It’s a physical change but a chemical change is also taking place i.e. burning of candle wick in air forming carbon dioxide and water.
o Brainstorm children by asking about different types of chemical and physical changes around them.
· Teacher can divide the class in tow 4 groups and assign them activity 1 and 2. After performing the experiment presenter from each group will share their observations and conclusions with other groups.
· Ask children to put one spoonful of salt into the cup A.
· Put some water into the cup and stir.
· Ask them to wait 15 seconds and observe what happens.
· Ask children following questions:
1) What happened when the water was added to the salt?
(Expected response: Salt dissolved completely in water)
2) Did a physical or chemical change happen?
(Expected response: A physical change has occurred as salt and water can be separated by evaporation)
· Assign the following activity to 2nd group.
· Put one spoonful of baking soda into the beaker/cup B.
· Put three spoonful’s of vinegar into the cup.
· Ask them to observe what happens and then answer following questions:
1. What happened when the vinegar was added to the baking soda?
(Expected response: Bubbles started rising in the cup. Tell them that this this is carbon dioxide and rising of bubbles is called effervescence)
2. Did a physical or chemical change happen?
(Expected response: It is a chemical reaction as new products are formed)
· Homogeneous mixtures are called solution.
· Solution can be in any physical state e.g. alloy is a solid-slid solution of metals; Air is a gas-gas solution etc.
· Upon filtration solution don’t leave a residue but suspension leave residue.
· Show students a piece of paper. Ask them to take 2 minutes to come up with examples of how this paper could physically change.
· Ask students to share their examples.
· Crumple or fold the paper to demonstrate physical change.
· Burn the tip of a piece of paper to demonstrate chemical change.
· Homogeneous mixtures are called solution.
· Solution can be in any physical state e.g. alloy is a solid-solid solution of metals; air is a gas solution etc.
· Upon filtration solution don’t leave residue.
Sum up / Conclusion
· Conclude lesson by telling children that they have learnt.
o In physical change the chemical properties are retained.
o In chemical change the chemical properties of reactants are lost.
· Teacher can assess students learning by asking them to write answers of following statements in their notebooks:
1. Cutting paper is a _______ change.
2. A melting ice cube is an example of a ______ change.
3. Burning fire is an example of a ________ change.
4. Boiling water is an example of a _________ change.
5. Rusting of iron is a ______________________ change.
· Find three examples of chemical and physical changes in everyday life. Explain why each of these changes is either chemical or physical.
· Show children following pictures and ask them to find out what kind of change occurs.
1. When you fry an egg
2. Light up fireworks
3. Change of color of autumn leaves.
4. Support your answer with logical reason.