When you boil an egg, the proteins inside denature. That means they change their shape and -- in this case -- harden. The heat causes the hardening. This is cause and effect. Cause and effect science projects should be accomplished using the scientific method. The scientific method calls on you to research and develop a question that you want answered, hypothesize and predict what will happen, experiment and then analyze what happened and draw conclusions.

Does salt added to boiling water increase the temperature of the water? This cause and effect experiment is for older students only with parental supervision. Pour 2 cups of water in a pan and bring the water to a boil for one minute on the stove. Insert a candy thermometer in the pan by attaching the candy thermometer to the side of the pan with the clip on the thermometer. Wait 60 seconds, and then record the temperature of the water.

Add 2 tablespoons of salt to the water and allow the water to boil for one minute, then record the temperature of the water in the same way.

Add another 2 tablespoons of salt to the water, boil for one minute, then record the temperature in the same way.

You have changed the salt concentration and nothing else, so if the boiling temperature changed then the difference in salt concentration caused the change.

Does music make a plant grow faster? Select two plants that are the same size, type and in the same type and size of container. Make sure both plants are healthy. Place each plant in a window that is exposed to full sunlight, and water both plants with the same amount of water each day. The plants should be in different rooms. Measure the height of the plants. Once a day play music for only one of the plants for about 1 hour. Select any type of music you desire, such as rock, classical music or pop. Over a period of two weeks note any differences in each plant’s growth.

Because this experiment takes so long, there are many other factors that could be different between the two plants, so you'll want to repeat this experiment several times.

Do any household cleaners cause motor oil to separate from water? This experiment is intended for older students with adult supervision. Place three glass jars side by side on a table. Pour 1 cup of water in each jar. Then pour 1 teaspoon of motor oil in each jar. Note what happens as the oil mixes with the water. In one jar pour 1 teaspoon of pine cleaner and note any effect it has on the oil and water. In the next jar pour 1 teaspoon of window cleaner and note any effect the cleaner has on the oil and water. In the last jar pour 1 teaspoon of dish washing liquid and see what happens to the oil and water. Compare the results in each jar. If the oil acts differently with each cleaner, then the cleaner has caused an effect on the oil distribution.

How does the angle of a slope affect the speed of a rolling ball? Take a flat three-foot plank and put it on a flat surface. Put a one-inch block under one end. Place a smooth ball of any sort -- a billiard ball, a bowling ball or a ping-pong ball, for example -- on the high end of the plank. Start a stopwatch when you let the ball roll and stop the timer when the ball stops. Replace the one-inch block with a two-inch block and repeat. Continue with a few more blocks. If the ball travels more slowly or more quickly, it's because you have changed the angle of the plank.