Things needed :
Two paper cups
Plaster of paris
Ø Take a cup of about 3 inches height.
Ø Prepare plaster of paris in the cup.
Ø Use the butter knife to cut a narrow one inch deep groove into the plaster of paris before it dries.
Ø The grooves should not touch the edges of the container.
Ø Allow it to dry completely.
Ø Carefully tear the container away to reveal your block. Measure the size of the groove. Fill the groove with water and place the block in the freezer.
Ø After the water has frozen, remove the block and record your observation. Allow the ice to melt and place it in the freezer again. Repeat this till the block brakes.