Last year my children each received about six pounds of candy from trick-or-treating. This year I set up a little “store” for them to trade their candy for some things they need or want like new pajamas, earrings, etc. I marked prices in advance as a percentage of their candy, since I couldn’t be sure how much they would get this year. I also wanted to leave them with a little. The main challenge was that my children are in second and fourth grades and have not yet learned percentages. However, since they know about 100 cents in a dollar and 100 centimeters in a meter (I use a Swedish sewing machine), we used the kilogram side of our kitchen scale, and it wasn’t too difficult.
I also like the presentation of teaching percentages at BBC Skillswise.