Lesson 1

The purpose of this lesson is for students to make sense of a hundred as a unit composed of 10 tens or 100 ones.

In grade 1, students were introduced to a ten as a unit made of 10 ones. They used that understanding to represent two-digit numbers and add within 100. Students used connecting cubes to make and break apart two-digit numbers. In previous units in grade 2, students used the words compose and decompose as they made and broke apart tens when they added and subtracted within 100.

In this lesson, students are introduced to the unit of a hundred. Building on the understanding that they can use 10 ones to compose a ten, students learn they can compose a hundred using 10 tens.

• Each group of 2 students needs access to at least 1 hundred block.

What unfinished learning or misunderstandings do your students have about composing tens and place value? How did you leverage those misconceptions in a positive way to further the understanding of the class?