paragraph: Oh no! Your younger sister just mixed up all of your LEGO parts. Now you have to put them all back into the original categories. How will you do this? You sort them by size and shape until they are each back into their specific place in the tray. What do you think you could have called the mess your younger sister created? Thats right, it is a mixture. Fortunately, it was a physical change and she just made a simple mixture. You are able to separate them back into order. Its a good thing she did not toss them into the fireplace. That would have caused a chemical change as they all melted together. If your LEGOs were melted, you would be out of luck for building that next big project. 
question: What do you have to put back into the original categories
answer: Your sister's LEGOs