One of the most common ideas about doing laundry is that there are some stains that are very hard to get out, or just won't come out at all. Some of these stains include ground-in dirt, mustard and ink. Test these opinions by testing the effectiveness of several of the most popular brands of detergent against these notorious stains. You will need multiple versions of each stain and identical pieces of cloth. Use a double-blind experiment in which the person judging the cleanliness of the items doesn't know which detergent was used for which item.
Many detergent manufacturers make the claim their you can save money on your electricity bill with their detergent because it works just as well in cold water. Put these assertions to the test by creating two sets of identically-stained clothes. Run one set through cold water and one through hot using one of these detergents. Pin the clothes on a poster board and label each for the judges to evaluate. Give a short presentation explaining the results and you methodology.
Another perennial question posed in laundromats across the country is whether powders or liquids are more effective at getting things clean. In this case, you will only need to use one kind of stain, but you should try several different types of liquid and powered detergents to see how they each do against this type of stain.
Another type of claim made by some detergent makers who add bleach to their product is that their detergents are color-safe. This one is easily tested with two identical garments. Wash one garment 20 to 30 times using the color-safe detergent. The other should remain unwashed and unused. When you are done, place both on a board to display the result.