We are learning about systems of equations in my small HS math class. Tomorrow, we will do mystery candy bags. I have done this before and used a scale and had one equation be their weights, but the scale was so sensitive that the answers were always off. So, I simplified it up and removed the scale/weights. I used Rolos, Kisses, and Peanut Butter cups. Each bag has at least one of each.
Last year I gave the kids the bag to solve but they squeezed it and tried to "feel" the answer. This year, they will see the bag - but no touching until they have done the math and have their guess. They will get an index card with some information on it:
There are 3 unknowns, so they will have to come up with three equations. I have a small class, so I only need 4 bags of mystery candy. You could do this without doing the bags of candy but it makes it more mysterious and the kids are motivated to solve it. I typed up all of the information for all the bags so when they are done, they can try to solve the other bags as well. Mystery Candy Worksheet