This is a great project I am currently working on with my 4th grade students. We signed up to research various products that are commonly bought at the supermarket. Some of the items we are researching include spinach, milk, wheat bread, turkey, cheese, and peanut butter. Every other week we collect data by shopping or calling the store. We record the date the information is collected, the quantity of the product (ounces or fluid ounces), and the price of the product. We use this information to calculate the unit price which we average by month and then track over time. The data is stored in an Access database. I have written reports that you can use to compile and then analyze the data.