Some easy science projects for a fourth grader include making a string phone to study sound waves or making crystals at home using salt water in a cup and some string. Additional projects can be found at Sciencekids.co.nz and Parenting.com.
To make a string phone, the fourth grader needs two plastic cups, a sewing needle and string. The child cuts a long piece of string and pokes a hole in the bottom of each cup. She threads the string through each cup and ties a knot at each end so the string is tightly tied to the cup. To use the string phone, one person is needed to hold each cup. Both people should distance themselves far enough so the string is tight. The child talks into the cup as she would a telephone and then puts her ear to the cup while the other person talks. This experiment demonstrates how sound waves travel through objects.
To grow salt crystals, the fourth grader needs a jar, some water, 1/2 cup of salt, a spoon for stirring, string, scissors and two toothpicks. She fills the jar with water and stirs in the salt. She mixes the solution together. Then she cuts a piece of string and ties both ends to a corresponding toothpick. She places the toothpicks on the lid of the jar so the string dangles into the middle of the water. The fourth grader leaves the string to sit for several days and waits for salt crystals to form on the string. This project is ideal for demonstrating crystal formation to fourth graders.