Think a preschooler is too young for chemistry? Science for Preschoolers website suggests creating a fun chemical reaction that will surprise young learners. In a balloon, place a tablespoon of baking soda. Then in a bottle, pour about an inch of vinegar. Place the lip of the balloon over the mouth of the bottle and allow the baking soda to fall in the vinegar. According to Science for Preschoolers in "Blow it Up" the reaction produces carbon dioxide which will blow up the balloon.
For another lesson in science, use a one pound box of cornstarch and mix it with 1 1/2 cups of water in a bowl. Then, if necessary, add water a tablespoon at a time until the mixture is runny. This will create a fun slime that provides a unique sensory experience for preschoolers. According to PBS Kids, when children poke the slime, the pressure causes it to turn back into a solid and the ingredients separate. But when playing with it gently, the cornstarch and water mix into the liquid.
Most 3 and 4-year-olds will enjoy the experience of planting a seed and watching something grow, but often they don't enjoy the waiting. Many plants grow very slowly and children lose interest. Lima beans, however, are a great choice to use with preschoolers because they are fast growing. Place some in a plastic bag with a wet paper towel and they will sprout within days. Then let children plant them in a cup with potting soil and they will almost be able to watch the plant grow. Even if they check on it daily they will be able to see the quick growth of a lima bean plant.
Children won't believe that you can make raisins dance. Fill a clear glass with a clear carbonated beverage. Then add four or five raisins to the glass and watch what happens. The carbonated bubbles will attach to the raisins and lift them up to the top of the glass. As the bubbles pop, the raisins will sink and the process starts again.
To show preschoolers how powerful the sun is and why we need to protect our skin with sunscreen, make artwork using dark paper and sunlight. Place items on the dark paper, such as leaves, keys, and other unique shapes cut out of paper. Place the paper in the sun for several hours and then remove the items. Children will be able to see how much the paper faded where the paper was not covered, and how the places they covered were protected.
Fill a small bowl with water and sprinkle black pepper over the top of the water. Dip your finger in the water to show students that nothing really happens by placing something in the bowl. Then dip your finger in some liquid soap and dip it back into the peppered bowl. The pepper will magically run away from your finger. According to Amazing Preschool Activities, the soap breaks the surface tension of the water, causing the water to move, which takes the pepper with it.