Lesson: Doubles Minus One Mathematics • 1st Grade

In this lesson, we will learn how to add two consecutive numbers with sums up to 20 by finding one less than a doubles fact.

Lesson Plan

Students will be able to

use models to solve addition problems by using the doubles minus one strategy,
solve addition problems by using the doubles minus one strategy without using models,
recognize situations in which doubles minus one is a reasonable strategy for solving addition problems,
solve word problems using the doubles minus one strategy.

Q1:

Notice that 3 is one less than 4.

If , which of the following is equal to ?

Q2:

Use

Q3:

Amelia tried to solve by using the doubling numbers facts, but she got the answer wrong.

Her teacher circled the mistake in her answer. Help her by finding .