As parents who have watched their child splashing in a mud puddle can attest, preschoolers love experimenting with water and other liquids, the ickier the better. Observing how liquids move and change can be a rich experience for young children but also a messy one. Before you toss your empty plastic bottles in the recycling bin, try repurposing them as sensory bottles for your early learner.
A common experiment for preschoolers is to try mixing oil with water. With your learner, fill a clear plastic bottle halfway with vegetable or mineral oil and halfway with water, adding food coloring if you like. No matter how much you shake it, oil is less dense than water and it will always float to the top, just like the oil and vinegar salad dressing in your refrigerator. To add a twist to this experiment, try squeezing a squirt of dish soap into your oil and water bottle. Soap helps water stick to oil, and your liquids will take much longer to separate after shaking.
Your child has probably also noticed that some liquids are more viscous, or thicker, than others. Liquids such as shampoo that seemingly take forever to squeeze from their bottles are more viscous than water. Try setting up a comparison between two liquids by filling one bottle with water and another with clear liquid soap, corn syrup or hair gel. Now drop a marble or dime into each bottle. Why does your child think one is moving more slowly than the other? Experiments like this one give your preschooler the opportunity to practice observing and describing what they see.
Finally, for those unafraid of mess, add a scoop of baking soda to a bottle filled halfway with a liquid soap and water mixture. Add a splash of vinegar and leave the cap off for this soapy twist on the classic kitchen volcano.