These are so easy to do with pillows and cases. They can fold into chairs, loungers, beds, or make a fort with two of them. Check out the pics on How to make a pillow chaise for children - Grandma's Briefs - It's not just for grandmas!
Paint that grows. Mix 1 cup flour, 3 tsp baking powder, 1 tsp salt, and enough water to make consistency of pancake batter. Divide into 4 parts and put in snack size Ziploc baggies along with food coloring. Squish it around to mix up the colors. Rubber band like icing bag and snip tiny hole. Squeeze to paint and then pop paper in microwave for 30-45 seconds and watch the paint puff up and grow.
Make watercolours at home! Baking Soda Vinegar Cornstarch Corn syrup Mixing bowl with spout Measuring Cups Whisk Food colouring Ice Cube tray Pour 1 cup of baking soda into bowl. Slowly pour 3/4 cup of vinegar (it will bubble and fizz, don't do it all at once!) When they've stopped bubbling, whisk the mixture. Add 2 tablespoons corn syrup. Add 1 cup cornstarch. Whisk the entire mixture until combined. Pour into ice trays. Colour each cube with food colouring. Allow to dry (up to 2 days).
Borax snowflakes - If you have Borax at home, you SO need to do this with the kids. Do it after dinner, and by breakfast the kids will be amazed at what has happened! We have 8 snowflakes hanging in our window just a-sparkling away!