Materials: 2 measuring cups one that will hold at least 2 cups of liquid, water and sugar
Place 1 cup of water in the larger cup and 1cup of sugar in the other cup
Pour the water into the cup with the sugar and stir.
What did you notice? First, all of the sugar did not dissolve into the water. Also if you check the cup measurement you do not have two cups. What happened? We have made a solution which means we have mixed ingredients and those ingredients may undergo a physical change. Some of the molecules of sugar have filled into the space between the water molecules. However, there was not enough space for all of the sugar to fit in and so the solution is now saturated.
Try the experiment again, but this time have three cups one filled with water at room temperature; one refrigerated and a cup of boiling water. Have students add sugar a tablespoonful of sugar to each cup and observe. They should see that the amount of sugar that dissolves depends on the temperature of the water. The higher the temperature the more thoroughly the sugar is dissolved. Place the cups to the side and allow them to cool. What happens? Students should see the solution reverse and the sugar separate back to the bottom of the cups as they cool.