Double It

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Objective

SWBAT use the addition of doubles to perform doubles subtraction and addition and subtraction with doubles plus/minus one.

Big Idea

Common Core standards state that students will be able to add and subtract within 20 using mental strategies. This lesson presents a set of these strategies.

Warm Up

10 minutes

I begin today by activating student's prior knowledge. I put the Partners of Ten Rhyme on the interactive white board. I ask students to chant it with me. I hide the rhyme and ask students who is the partner with 8 (who does 8 like?) I ask a few other partner questions to help students recall the rhyme we have already been using.

I put some partners of ten subtraction problems on the board.

10 - 3 =___. 10 - 6 = ___. 10 - 5 =____ for students to solve without counting. I ask students to call out the answers. This may be loud, but I am not checking each child here for understanding. I am watching though, to see who seems to not be responding.

How does knowing partners of 10 help us with subtraction from 10? I ask several students to answer.

Are there other things we can do to help us with adding and subtracting easily?

I tell students that today we will work on a few of those strategies.

Teaching The Lesson

20 minutes

I start by introducing the word double. What does double mean? If I double something what do I do?

Doubles help us with other math facts. Can you think of a double? (Students suggest 2 + 2, etc.). I write responses on the board as students suggest them.

What happens when I double something in math? (I add the same number twice.)

I tell students that I would like to make a doubles rhyme that is like the partners of ten rhyme, but using the doubles. I say I will start with 1.

One plus one is two, I better tie my shoe.

Together we try two.

Two plus two is ____  . I ask for the answer. Now I ask for a rhyme.

I tell students that they will start today by working with a partner to write a double rhyme for the number given to them and to draw a picture that goes with it.  When it is done we'll share and try them to see if the rhymes will help us just like the tens rhyme does.

I hand each group a paper with a place for the rhyme, the picture and their number (3, 4, 5, 6, 7, 8, 9, 10, 11, 12).

I give groups about 5 minutes to write and illustrate their rhyme. We post our work and then read each rhyme together.

We will use these rhymes as we practice during the next part of the lesson.

Independent Practice

15 minutes

In this part of the lesson students make doubles pictures that have a picture of a number of items on the top, the same number on the bottom and an addition and subtraction sentence for each picture. The pictures will be drawn on cards creating a class set of flash cards for the doubles facts.

After drawing the cards I call out a doubles fact. Any child with that card brings it up to me.

Closing

10 minutes

Students complete a doubles practice page to act as an informal assessment of understanding of doubles.

This can be two different pages to accommodate different levels in the classroom. If students are using strategies to add these numbers, they should show their work. Many students may opt to use their fingers, so during this work time I'm circulating to take note of this type of strategy use.