Every preschoolers loves dinosaurs. For this activity, all you need are small plastic dinosaurs and ice trays. Put a dinosaur in each ice tray square, and fill the tray with water. Allow to freeze.
Give each child a paper plate with one ice cube and a small wooden mallet. Explain to them that a paleontologist is a scientist who looks for dinosaur bones. Tell them that they get to play paleontologist by finding the dinosaur in the ice. Let them bang on the ice cubes and break out their toy dinosaurs.
Fill bowls of water and stick an ice cube into each bowl. Set a bowl in front of each preschooler. Give each child a piece of string and ask them to use the string to pick up the ice. It will be impossible (though fun to try). Then the children to lay their piece of string across the ice cube. Give them each a pinch of salt and let them sprinkle the salt onto the ice.
Have the group count to ten and tell them to lift the ice with the string. The string will magically stick to the ice!
Explain how a bear keeps warm during the winter--with a layer of blubber between his coat and his body. Use this experiment to show the preschoolers how the blubber keeps bears warm.
Fill two buckets with water. Add ice to both buckets. Have the preschooler put one hand into one bucket of ice water and feel how cold it is. Then have the child put a latex glove on the other hand. Put the gloved hand into a baggie that is pre-filled with vegetable oil. Hold the baggie around the child's wrist with your hand.
Let the child reach the baggied hand into the other bucket of ice water. The oil will keep the hand from getting cold. Have the child tell you what it feels like, and explain that the oil is a barrier against the cold, like the blubber that a bear has to protect him from the cold as well.