In this set of challenges, you have the opportunity to investigate a sequence of lessons, called Patterning and Partitioning, taught over a period of five weeks (mid-September to late October) in a first-grade classroom. In these lessons, the teacher wants to help the students develop deep understandings of number concepts, with an emphasis on number relationships. She wants the students to move beyond counting and see, for example, that six is one more than five, as well as three plus three, and four less than ten. She also wants to introduce the students to addition and subtraction of sums less than twenty. The teacher has indicated that, although the students’ scores on most tests of academic achievement are widespread, they are quite advanced as a group. In addition, the teacher points out they are a reasonably well-behaved class.