In working out exercises in addition the author became convinced of the importance of the ones place of the mind and fashioned a carefully worked technique in order to free the student from having to think about technique. (Author/RK)

Students who can compute mathematical problems in their heads have learned a skill that is important for estimating and for understanding the number system. Practice activities that can help students master mental computation skills are described. (PP)

Primary students can learn about computation and estimation by reading a story about the use of money, then following up with estimation and calculation activities. Intermediate students can explore the relationship between addition and multiplication using a computation game, collaborating on when, how, and why they use addition and…