Thinking of a literacy/numeracy activity for your 100th day celebrations?
Try searching for lesson plans written for the book, One Hundred Hungry Ants.
Click here to preview the book. It was recently in Scholastic's book order for February and can still be ordered through them.
Sorry, grade 8s. You'll have to do your own search. (Or how about having the grade 8 students TEACH one of the lessons above TO a lower grade? To teach something requires a lot more mastery of the subject.)