Products often cost less per unit if they are purchased in larger sizes or in bulk. Suppose a 10-ounce bag of potato chips costs $3.99, and a two-ounce bag costs 99 cents. Determine the cost per ounce by diving the total cost by the number of ounces in the bag. In this example, chips cost 39.9 cents per ounce when purchased in the large bag and 49.5 cents per ounce in the small bag. Obviously, it saves you money if you buy the larger size. Since potato chips come in packages, you must buy five small bags of our example chips to get the equivalent product in one large bag.
Does buying the larger size have another benefit besides a cost savings, namely that there is less packaging material that will end up in a landfill after it is discarded? Buy a large bag of chips and several small bags in order to get the equivalent ounces of chips contained in the large bag. Using a gram weight scale, weigh the empty large package. Place all of the smaller bags on the scale and weigh them too. Compare the weights and determine if buying chips in a larger package helps the environment because less packaging material is used. Invite your friends to enjoy the chips after you empty the bags.
Does a rainstorm clean the air by removing airborne particles, such as smoke, pollen, dust and other particulate matter? Monitor the weather forecast and wait for a day when a long, steady rain is predicted. At the start of the storm, collect a test tube full of rainwater and label it "start." After at least five or six hours of steady rain, collect another sample of rain water in a separate test tube and label it "end." Compare the water collected at the beginning with the water collected at the end to see if there is a difference. Use a magnifying glass and a microscope. Test the pH of your samples with litmus paper. Has the air been scrubbed clean by the rain? Is the air cleaner after a storm in the city than in the country?
Hypothesize that you can predict how many of each color of multicolored candies are in a bag before you open it. To test your hypothesis you will need to have a large sample size and evaluate the contents of many bags. Use a computer spreadsheet program to set up a table to enter data. Label the left most column "Color" and type a color on each row underneath it (red, yellow, brown, etc.). Label the next columns "Bag #1," "Bag #2," etc. up to "Bag #20." Purchase 20 bags of multicolored candy. Open one bag at a time and count each color. Enter the amounts into your spreadsheet. You can also use your spreadsheet to determine the percentage of each color compared to the whole bag. The formula for finding percent is to multiply the number of each color of candy divided by the total number of candies in the bag, and then multiply the result by 100 to convert to percent. Based on your data, make prediction as to what percentage of each color will be in the average bag of candy, and then open a dozen new bags and compare your prediction to the actual number of colored candies in each bag.
The earth's crust may seem solid to you, but it floats on a layer of molten material. There are several large sections of earth, or "tectonic plates," that float and there are other places where they butt together. Pressure builds up where these plates collide and the pressure is released by one plate sliding over another, by both being pushed up, or by buckling and rippling occurring. This process results in earthquakes.
Demonstrate this collision by baking a cake in a square or rectangle pan. Once the cake has cooled, run a knife around the inside edge of the pan to separate the cake from the sides. Also make a cut down the middle of the cake. Take two wide spatulas and place them at opposite ends of the outside edges, with the cut across the middle. Slowly push the two "plates" together and observe what happens at the colliding boundary in the middle. When your project is done, serve the cake to your family.