Some fun and easy science projects for toddlers include Floating Eggs, Oil and Water and Dissolving Sugar. These projects are easy to do and can be done with items from around the house.
When placing an egg in normal water it will sink to the bottom, but when salt is added to the water the egg will float to the top. When oil and water are mixed together in a glass the two will separate and make two different layers in the glass. When sugar is added to water of different temperatures it will dissolve at different rates. The warmer the water the faster it will dissolve.