ABSTRACT
Subtraction is generally introduced after addition and initially modeled as a take-away situation. Students begin with a total set of counters, take away some of them, and find the number of counters that are left. Over time, students also explore subtraction as a missing addend or as a comparison, and counting strategies may replace modeling with drawings or manipulatives. Students are likely to develop fluency with totals to 100 and extend the exploration of subtraction with totals to 1,000 in second grade. A kindergarten teacher invites the students to the rug area and introduces the game using five counters. Teams take turns placing a playing card beneath a board number and finding the difference. Communicating mathematical ideas and sharing mathematical thinking are essential habits of mind. Students correctly identify that the number is greater than 230. Estimation skills are essential; we typically use them every day.
