I use this activity at Halloween. I buy several bags of candy and make copies of the nutritional charts on the backs of the bag to give the students to use for their data. (At the end of the period, I give them some of the candy.)
Students will gather data on calories and fat grams in each serving of candy. They will then see if there is a correlation between weight and calories and between weight and fat grams. Students will determine the correlation and calculate the regression line to determine how well it fits the data.