Click the link above (it takes you right to the activity) and download a .pdf of a candy log:
Give it to students a few days before Halloween. If you're having a Halloween party at school, it should go out before then. Students can keep a record of what kinds of candy they got during trick-or-treating. Even if some kids don't go trick-or-treating, they can keep a record of what kinds of candy they got during the Halloween party, or what they ate over the weekend.
During the week after Halloween, collect the data forms and use them to teach students about various kinds of graphs and charts, like circle graphs, bar graphs, line graphs or pictographs. Combine everyone's data and hang a chart of your findings around the room.
From the link, here's an example using tally marks:
This could also be used to apply skills for probability, fractions and percents ("What percent of the class received candy bars during Halloween?").
The activity works for several holidays. Have them keep a record of what kind of dishes they eat during Thanksgiving, what kind of presents they receive during Christmas, etc. It's a great way to keep them on their toes.