CU 4.09Friction

1. 1

   Set the block on the wax paper strip. Pull the rubber band slowly until the block starts to slide.

2. 2

   Say: 'Look how little the rubber band stretched. The block slid easily.'

3. 3

   Put the block on the sandpaper and pull the same way. Watch the band stretch much longer before the block moves.

4. 4

   Say: 'The rough sandpaper rubs against the block and holds it back. This rubbing is called friction.'

5. 5

   Test the smooth wood and the felt.

6. 6

   Invite the child to test each strip and line them up from easiest to hardest.

7. 7

   Feel the bottom of a shoe together and talk about why it is bumpy.

What catches the child’s eye

• The rubber band stretching long on sandpaper before the block suddenly jumps forward
• Hands growing warm after rubbing them together

Extensions, easiest to hardest

1. Predict the order before testing
2. Rub hands together fast and feel them warm up
3. Slide in socks and in shoes on the same floor and compare
4. Talk about why people put sand or salt on icy Utah sidewalks