Lesson objective: Apply place value concept that ten groups of ten is equivalent to 100.

This lesson provides an opportunity for students to apply their knowledge and understanding of composing tens to make 100 to a mathematical situation. Students are asked to determine how many more items, grouped into tens, are needed to make 100 so their teacher can have enough for a class party.

Key Concept students will use:

- a bundle of ten tens can be thought of as a hundred

Skills students will use:

- understanding of place value to add ten to multiples of ten (Grade 1, Unit 14)
- a ten is a unit of ten ones (Grade 1, Unit 1)
- adding numbers within 100 using place value concepts (Grade 2, Unit 1)

Students engage in Mathematical Practice 7 (Making sense of structure) as they understand the value of a digit in a number and move on from only place naming, thus building the structure of the base-ten system. It builds understanding that ten tens makes a hundred.

**Key vocabulary: **

- grouping
- hundred
- skip count
- strategies
- tens

**Special materials needed:**

- base ten blocks - tens and hundreds