Some good science projects for third graders are effective hand washing, which shows the children the best way to wash their hands, how to separate salt from water, how to make an equatorial sundial and snowflakes. All these projects aim to teach the children important scientific principles.
In the experiment for effective hand washing, the child rubs Glo Germ on his hands, then he washes his hands with regular soap and water. After viewing his hands under a UV light, he takes a photo of the results. The child then reapplies the Glo Germ to his hands, and repeats the process with anti-bacterial soap and with anti-bacterial gel.
To perform the experiment separating salt from water, the child needs black paper, a baking sheet and salt water. The salt must be dissolved in the water. After laying the black paper on the baking sheet, pour the salt water over it and cover it with another sheet of black paper. Leave the baking sheet out in the sun or somewhere warm where the sun can reach it. Once the water evaporates, only recrystallized salt is left behind.
In the equatorial sundial experiment, the child constructs a sundial that can be tested in any sunny spot to show reasonably accurate time using its shadow.
The snowflake experiment has the child researching snow and snow crystallization. The child may make snowflakes from paper or grow his own snowflake crystals.