Book Description: Celebrate 20 years of Mathematics Their Way -- the complete curriculum to replace, support, or supplement your existing program -- with the new 20th Anniversary Edition. No teacher resource in recent decades has had a greater impact on primary mathematics education than Mary Baratt-Lorton’s Mathematics Their Way. The popularity of this developmental, activity-based mathematics program began slowly from its publication in 1976, and grew steadily. By the late 1980’s, it not only began to dominate how primary teachers thought about teaching math, but its philosophy began to permeate the entire elementary math curriculum. The goal of the activities is to develop understanding and insight of the patterns of math through the use of concrete materials. Students will discover and explore while developing skills in addition, subtraction, pattern recognition, measurement, and more. The newly revised Teacher Sourcebook includes special chapter bookmarks that refer you to key activities in the MTW Summary Newsletter, plus blackline masters and a new index that also references the Newsletter.