How to teach volume of irregular objects?

 OBJECTIVES

     At any point in the discussion, the students should be able to:

1. differentiate objects with regular and irregular shapes;

2. compute for the volume of the irregularly-shaped object, and;

3. use measuring instruments correctly.

MATERIALS
small rock sample, measuring cup, water, beakers, 

LEARNING TASK

Motivation - Show a wooden block and a small rock sample. Have the samples passed around the classroom.

Ask: Which between the two samples has bigger space? How did you know?

Recall the students knowledge in getting the volume of regularly-shaped objects.

Lesson Proper

1. Solicit students' ideas on how to get the volume of the piece of rock. Write their answers on the board. Do not reveal yet the answer.

2. Show a measuring cup to the kids. Ask: How are you going to measure the space occupied by the rock using this cup?
3. Make the cup half-filled with water.
4. Ask one student to read the level of water. Write the reading on the board.
5. Ask: What do you think will happen if I put this small rock inside the cup?
6. Call somebody to put the rock sample in the container.
7. Ask somebody to get the level of water.
8. Write the reading on the board.
9. Ask: Now we have two readings of water level on the board. What should we do with these values to get the total space occupied by the rock inside the cup? ( Answer: Subtract --> Water level 2-Water level 1)
10. Ask: Why did the water displaced when you put the rock in? (Recall: No two matter can occupy the same space) Introduce the term, WATER DISPLACEMENT METHOD.
11. Aside from this rock sample, what other objects can be considered irregularly-shaped objects?

Water Displacement Method

Group Activity: Round Robin Strategy

11. Provide four learning stations with a beaker and irregular object.
     Example: Station 1 - shell
                    Station 2 - toy
                    Station 3 - key chain
                    Station 4 - small figurine
12. Assign each group a specific station to start with.
13. Instruct the group to get the volume of the irregular object in each station.
14. Instruct the pupils to go to the next station when they hear a bell.
15. Have the pupils write down their computations in each station.

Generalization

16. Ask: How are irregularly-shaped objects different from regularly-shaped objects?
             What is water displacement method? How is it done?