Try the following conservation interview with a child between the ages of five and eight. After you have finished, try it again with an older child.

1		Place identical glasses on the table and fill them with different amounts of water (colored water is even better). Ask the child to make them the same by pouring more water. Make sure the child feels that they are equal before proceeding.
2		Add a third glass of different dimensions. Place the screen or piece of paper in front of the glasses so that the tops are visible but the water levels are not. Pour the water from one of the identical glasses to the new glass. Ask the child whether one glass has more or if they are the same. Ask the child to explain the answer. Record child’s answer:
3		Pour the water back and ask the same question. Record child’s answer:
4		Repeat step 2 without the screen. Record child’s answer:
5		Repeat step 3 without the screen. Record child’s answer: