Lesson objective: Extend understanding of one bundle of ten representing 10 in a teen number.

Students bring prior knowledge of one bundle of ten from 1.NBT.B.2.A - 10 can be thought of as a bundle of ten ones — called a "ten." This prior knowledge is extended to teen numbers as students count the number of ones beyond a bundle of ten. A conceptual challenge students may encounter is the one in the teen number represeting 10 units. Students may still think of teen numbers as single counts where the number "14" is part of a count that follows 13 and preceeds 15. Therefore, they have a difficult time grasping the concept of the digit 1 represting a "bundle" in a number.

The concept is developed through work with a tens frame and some form of counter, which gives students a visual of one group of ten in one tens frame and some ones left over in another.

This work helps students deepen their understanding of number because the representation of the didgits, one equalling 10 and the other representing single ones, develops their ideas about place value.

Students engage in Mathematical Practice 2, reason abstractly and quantitatively as they develop the relationship between the quantity a teen number represents and the digits that represent the quantity.

**Key vocabulary:**

- digit
- number
- numeral
- ones
- ten
- tens

**Special materials needed:**

- counters (circle counters, linking cubes, any item that students can pick up and manipulate on a tens frame.
- tens frame