This simple science project only takes a few materials and a little bit of work. Purchase two plants of the same type. Place both plants in the sunshine and water them each day. Give each of them the exact same amount of water each time you water them. For 30 minutes each day, move one plant to another sunny location. Play the plant classical music for the entire 30 minutes. Take the plant back to its original location afterward. Record your observations each day for a month. Include any variables that may interfere with the experiment: cold air, fumes, etc. Watch to see if there is a difference between the two plants. Look for leaf color, rate of growth and other effects.
A salt crystal garden is impressive looking to any fourth grader. Grow your own crystal garden using only five ingredients: 3 tbsp. salt, 3 tbsp. food coloring, 3 tbsp. water, 3 tbsp. ammonia and a few charcoal briquettes. Mix the first four ingredients together, then pour the mixture over the charcoal briquettes. Place the briquettes in a shallow bowl before pouring. The mixture needs to come up to at least half-way on the briquettes for the experiment to work well. Crystals will begin growing hours later. Observe the crystals as they grow and report on their growth.
Demonstrating how erosion takes place is a unique, easy fourth grade science project. It's possible to demonstrate wind and water erosion. Fill two large, plastic tubs with soil. Two to three gallons of soil per tub is efficient. Shape the soil to create a mound in each tub. Set the tubs side by side outside. Leave the lid off one tub. This one will be observed for wind erosion. Record your observations each day for a week. Place a lid on the other tub during this time. This will prevent the wind from getting to the soil. Once a day, pour 3/4 ounces of water over the top of the mound each day for seven days straight. Record your observations. Don't forget to measure the mound before you begin the erosion experiment. At the end of the week, remeasure the mound using a tape measure to see if it is any shorter. Record your data.
An extremely easy fourth grade science project is demonstrating light refraction, or bending light. Fill a clear juice glass half-way with fresh, clean water. Place a pencil in the glass. The pencil will lay against the side of the glass. From above, the pencil looks normal. However, when you look into the side of the glass, the pencil looks as if it is bent. This shows how light moves slower through water than it does through air. Record your observations and take photos if necessary.