Fall Leaves and Unknown Numbers

     Today was the perfect day for a Fall Themed Math Lesson.  We began math with students drawing a bare tree taking up most of their paper.  Then, they gathered 9 - 13 fall colored leaves and placed them on their tree.
     Students then became the wind and gave one strong puff against their tree and watched some of the leaves fall.   It was their job to figure out how many leaves blew off the tree without counting them.  Instead, students had to think about how many leaves were on the tree & how many they had on the tree now.   Would they count up or count back to find the answer?