The Big Dig activity is a project that you will enjoy completing over several weeks. It gives you the tools to figure out the age-old question of what happens after you throw trash away. The terms and concepts mentioned in Background tab are very important to cover before the activity starts. You will need to have your scholar define these with a reliable source; the bibliography at the bottom of the page offers some good sites. The materials are easily attainable; the tricky part is deciding which materials you are going to test. The resource recommends having five different samples of similar things. I think one of the easiest things you can test are packaging materials. I do not have a backyard so what we decided to cut down the material into small one-inch squares and bury them in buckets full of soil. I would recommend doing two buckets of identical materials and uncover one halfway through your test period so that you can collect another data point. Have your child make predictions about which one will biodegrade faster/slower and report their results.