As larger sets become combined or separated, counting with one to one correspondence becomes overwhelming and more efficient mathematical processes take the place of rote counting. Addition is the combining of two sets. Subtraction is the removal of one set from another set. While initial computation strategies rely heavily on counting every item in the sets, advanced stages of computation (often referred to as strategic counting) rely less on counting and more about the flexibility with which students compose and decompose numbers while maintaining equivalence. Students should progress across the following stages of computation in order to establish the prerequisite concepts and skills necessary for place value and multi-digit algorithms.

  1. Count All – Take Away

  2. Count On – Think Addition

  3. Make 5 – Across 5

  4. Make 10 – Across 10