Third-grade science projects are many grade-schoolers' first introduction to science and can be very exciting. As a parent, you are in a unique position to encourage your child's interest in science while guiding him in creating a good write-up of his project. Third-grade reports need not be overly detailed or lengthy, but can realistically be structured similarly to the science reports required of students in higher grades.
State in one sentence what your experimental question is. In other words, what is the point of the experiment and what are you trying to discover?
List all of the materials involved with the project.
Write out the steps of the procedure, with enough clarity that someone else would be able to pick them up and recreate your experiment.
In a few sentences write out your experimental findings. Summarize any numerical data that you obtained from the experiment and state what you think it means.
Make a conclusion about the significance of your data to the experiment.
Suggest any future experiments, similar to this project, that you would like to complete.