Conduct this experiment to investigate the effects of different environments on the rusting process. Place four identical beakers next to one another and place a soap-free steel wool pad in the center of each one. Leave one beaker with just a steel wool pad inside --- this is your control. In the remaining three beakers, add a cup of water, half a cup of water and half a cup of vinegar, and a cup of vinegar, respectively. Once each of your beakers is prepared, start a timer and return once every 20 minutes to observe the rust level. The amount of rust occurring in each beaker is your dependent variable.
In this experiment, the independent variables are the identical plant setups, which includes using identical plant pots and potting soil, and watering the plants with the same volume of water every other day. The dependent variable is the extent to which the plant grows, such as its height and width (or span). Fill two identical polystyrene cups three-quarters of the way with potting soil and plant a pair of runner bean seedlings a quarter inch beneath the surface of the soil in each one. Water each of the plants with a controlled volume of water, such as half a cup. Place one plant on a windowsill with natural light and the other underneath a plastic bucket in a darkened room. Check back on your plants and measure their width and height in inches once a day. Water your plants every other day. Conclude your experiment after no less than three weeks and compare growth for plants in light and dark.
This classic chemistry experiment can demonstrate your control over dependent variables. In this project, the dependent variable is the time it takes for a balloon to burst. The independent variables are a plastic bottle, size and thickness of balloons and the amounts of baking soda and vinegar used. Set up your experiment by placing a clean, empty plastic bottle in a deep sink. To test the different amounts of vinegar and baking soda, add soda into the bottle before pouring vinegar through a funnel and quickly placing the neck of a balloon over the top of the bottle and starting a timer (you can also ask a friend or classmate to start the timer). Stop the timer once the balloon bursts. Test different amounts of baking soda and vinegar during this experiment, such as half a cup of baking soda and a medicine dropper full of vinegar, and graph the reactions between the varying amounts of the two substances.
In this physics experiment, the level of microamps (current) is the dependent variable, while the independent variables are the different fruits and vegetables used and the method used to measure electric charge. Select several different items of fruit and/or vegetables, such as lemons, apples, potatoes and leeks, and devise a set system for measuring current, such as inserting the two probes of a multimeter 3 inches apart and 2 inches deep into each fruit or vegetable. Test each vegetable twice and take an average of the two results to ensure experiment validity before determining which fruits and vegetables have the least and most electric charge.