Surf into Science 3:	 How Pulleys Work	 		 			

The student will be able to:

demonstrate how pulleys work.


Activities:	

Arrange the students in groups of four.


Activity 1:

1.	Two students stand apart holding the ends of a round bar, such as a broom handle, 
	at waist height. 

2.	A small bucket of sand is placed on the floor below the middle of the bar. Each 
	student should lift the bar to realize its weight.

3.	One student ties one end of the rope to the handle and loops the remainder of the 
	rope over the bar.

4. 	Another student will use the bar for a pulley as he/she hoists the bucket of sand.

5.	Have students take turns until all members of the group has had a turn hoisting 
	the bucket.


Activity 2:

Repeat Activity 1, this time using a pulley attached to a board to lift the bucket of sand. 
Only differences this time, a length of board and pulley replaces the round bar.

Discussion:	 
		
1.	What were the differences between the two activities?

2.	Which activity made it easier to lift the bucket?  Explain.

3.	Did you have to work as hard or harder to lift the bucket using the pulley or was it
	easier without the pulley?

Explain that they have just used a fixed pulley.


Activity 3:

Set up this activity like Activity 1, but this time have the end of the rope tied to the round bar. Loop the rope through the bucket handle (moveable pulley) and then over the top of the bar. Now pull on the rope to lift the bucket.

Discussion:

1. 	What were the differences between the three activities?

2.	Which activity made it easier to lift the bucket?  Explain.
 
 
Assessment:

Circulate, observe, and ask questions as each child participates in the activities.

Observe the child's social interactions with other class members.