Three-year-olds are curious about the world, and they already ask questions. It's easy to foster this into more observation by asking them leading questions about what they see and hear. For example, if the child points out a caterpillar, you can ask, "What color is it?" or "Does it look soft or hard?" Nature walks allow you to foster your child's observational skills. After you are finished, let him draw or write about what he saw.
Children love to make messes. If you want to try a fun but messy experiment, mix together some water and cornstarch until it is a thick liquid. Let the child dip a finger in, and ask if it is a solid or a liquid. Then pour some in his hand and have him squeeze it tight. It will turn into a solid ball! Have him let go again and watch it turn back into a liquid. Parents should note that this mixture should be thrown away and not put down the sink.
You can make a silly putty-like substance if you mix together 1 cup of school glue to 1/2 cup of liquid starch. Stir it until it gains a stringy consistency. You may add more starch if you need to. Once the putty is ready, ask your child if this reminds him of anything around the house. Is it like the table? No, the table is hard. Is it like a rubber band? When he says yes, tell him that it is because the putty and the rubber band are both elastic.
Magnets are a fun everyday object for preschoolers. Get some magnets, some metal objects in different sizes, such as paper clips or drink coasters, and some non-metal items, like paper, wood or plastic. Have your child try to pick up the different objects. Which things stick to the magnets? Which ones don't? If you have magnets on the refrigerator, ask the child what he thinks it's made of. Is it like his clothes? Or is it like a paperclip?