SWBAT join a set of 3 numbers through addition.

My students have worked on joining 3 addends using drawings, objects, and equations. This lesson will supply concentrated practice on solving 3 addend equations with sums less than or equal to 20.

5 minutes

For the last two lessons, Word Problems with 3 Addends and Strategies for Word Problems, we have been working on developing a tool box of ideas to use for solving word problems, with both 2 and 3 addends. I will review with my class using the following discussion questions before we begin today's lesson.

*What kind of math work have we been doing the last few days? (Story problems, word problems)**How have we been solving them? (draw a picture, use tally marks, use objects in the room, using symbols, write a math problem)**I'm going to pick 2 people; what is your favorite way to solve a word problem? Why?(I like to draw a picture because then I can see everything. I like to write a number sentence because it is faster.)*

5 minutes

I will gather my students around me at the chalkboard and write in a vertical column 4+2+6. I am teaching my students to solve this problem using a two step process:

1. Pick two numbers and circle them, add them together and write the answer to the right of the problem.

2. Add the answer they wrote to the side to the number that is left. Their new answer goes under the line.

You may even encourage students to combine numbers in 3 addend problems strategically. For instance, with 4+2+6, it’s easiest to combine the 4 and 6 to make 10 and then add 2, or combine the 2 and 4 to make 6 and then it’s a doubles fact (1.OA.B.3).

I will complete several examples with numbers whose sums equal 20 or less. The Common Core standards want my first graders to be able to solve word problems with 3 addends. This can be accomplished by teaching them multiple possibilities to problem solve and find their sum. (1.OA.A.2). Using symbols to develop an equation is one method to solve a 3 addend word problem and I want to teach them the above process to find success with their equations. Check out my examples and view my multi-step process video.

10 minutes

I will go to TLS Books and print off the 3 addend practice sheet from the math practice packet here. I will have my students practice adding 3 numbers using the process I taught them in the Whole Group section. Watch the video in the resource section of one student getting started. I know I have several students who may get lost in the process of the different steps, but it is important to encourage them to stick with it and persevere until they find the answer that makes sense. (MP1) In later grades, the CCSS will have students begin to tackle Algebraic expressions that will require multiple steps. This simple introduction will help lay a foundation for this process. You can watch our process video here.

5 minutes

I will ask a few questions of my class, but have them respond to their groups. This will review the key notes in our lesson.

*What should I do first if I have 3 number to add together? (add a known math fact; doubles fact,2 numbers that equal 10, etc., pick 2 numbers to add)**What do I do after I add 2 numbers together?(add the last number to the first answer)*