# Let's Build It! Two-Digit Addition

Let’s start building numbers! Just as building skyscrapers is a visual representation of mathematics, students will use the visual representation of base-ten blocks to add—or build—onto a two-digit number.
Need extra help for EL students? Try the Base-Ten Block Sketches pre-lesson.
##### View aligned standards
Need extra help for EL students? Try the Base-Ten Block Sketches pre-lesson.

Build up your students’ addition skills using base-ten blocks. In this lesson plan, Let’s Build It! Two-Digit Addition, first graders will use visual representations to help them add multiples of 10 to two-digit numbers. It’s a great way to practice counting by tens and opens up a discussion about place value and two-digit numbers. By using a mix of learning tools, from whiteboards to base-ten blocks, this lesson uses several different teaching techniques to reinforce math concepts.

#### Learning Objectives

Students will be able to add two-digit numbers using both actual and written base-ten blocks.

The adjustment to the whole group lesson is a modification to differentiate for children who are English learners.

#### Introduction

(5 minutes)
• Practice counting by tens as a class. As you count, hold up the base-ten rods so that, at the end, you will be holding 10 rods to equal 100.
• Show on the board how adding 10 over and over is counting up and building bigger numbers.
• Call on students quickly and have them solve problems in which they add 10 every time (50 + 10, 30 + 10, 10 + 10).
• Say, “Base-ten blocks help us have a visual of what we are adding, especially when we are adding larger two-digit numbers.”

Beginning

• Ask students how many fingers they have, and count 10 fingers together chorally. Next, have 10 students flash 10 fingers as you count together by tens to 100.

Intermediate

• Display a hundreds chart as a visual reference as students solve problems of 10 more.