Let's Practice Adding Four Addends!

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Objective

SWBAT use their own strategies to add four two-digit addends.

Big Idea

Students have been working on regrouping when using four two digit addends for the last two days. This lesson allows time for students to practice their strategies and work on making sure their work is accurate.

Hook /Whole Class Game

10 minutes

We are going to start today by playing a game.  You will work with a group of four.  I will put a problem on the board. One person in the group will solve the problem while others "coach".  What are some ways that you could coach the person who is solving the problem for your group? 

I encourage students to say things like "Try this..."  or "Make sure you...." when they are coaching their teammates. 

Have students sit in heterogeneous groups of four or five on the rug or in their desks.  Give one student a white board and marker in each group.  I post a four addend problem on the board and allow students to work together to solve the problem.  

Depending on student engagement, student understanding, and time you can do between 2-6 practice problems.  This grouping allows students time to practice, give students opportunities to give each other feedback, and enables students to try different mathematical strategies. 

I chose to put my students in groups of four because I want to give them lots of chances to watch their teammates' strategies and to critique the reasoning of others. Since this is our third day of working on four or more addend problems, I find that it is valuable for students to see each other's strategies in action and to be able to coach their teammates.  Additionally, in this game, I want to encourage discussion and debate between students about their strategies. 

 

Strategy Share

15 minutes

Now that we have warmed up, we are going to do a strategy share.  On your white boards, I want you to show me how to solve this problem. 

32+17+24 +39 =

I hand out white boards and markers and allow students to use any strategy that works for them.  My students should have a tool belt of strategies for this kind of problem already but if they are struggling, I encourage them to think about using tens and ones or using column addition. 

I allow students 3-5 minutes to solve the problem.  Then I ask two or three students to share their strategies. 

When you share your strategy I want you to show us how you solved the problem, why you chose that strategy, and what you did to make sure your work was accurate. How did you check your work?(Attending to precision (MP6) is extremely important in these types of problems and should be addressed during strategy shares and teacher circulation so that students can gain the habit of checking their work using various strategies--using another strategy to make sure you are correct,  asking a friend to check your work,  reversing an addition sentence into a subtraction sentence to check, etc.) 

If you are listening to someone share their strategy, ask yourself:  1) How is this strategy similar or different from my strategy?   2) How could I use this strategy in the future?

In this video, a student shares two different strategies and explain which strategy she will likely use in the future: 

 

A strategy share is important because it (1) validates that there are multiple ways to solve a problem, (2) Gives students opportunities to share their own ideas about how to solve a particular problem, (3) Gives students new ideas about how to solve problems, and (4) Allows struggling students to hear strategies from their peers instead of from their teacher.  Additionally, these kinds of shares enable students to show their ability to use tools strategically (MP5) and give the teacher a sense of which tools/ strategies students are most comfortable with and which tools/strategies need to be further developed. 

Independent Practice

10 minutes

Independent practice is tiered based on proficiency with this skill (use previous days' work as well as work during the strategy share to inform groupings).  All students will have access to manipulatives (cubes, place value blocks, etc.), though in my experience, group A and some students in group B are the most likely to use the manipulatives. 

As students work, I circulate to support students who are struggling and to observe what strategies students are using and further, which strategies are yielding accurate results. 

Group A: In need of intervention

Students in this group will work with teacher to add four numbers (10-40).  This group will spend time exploring the tens and ones strategy since this strategy allows them to concretely represent each number and to be more accurate in their addition.  Students in this group will not be expected to regroup into the hundreds place. 

Group B: Right on track!

Students in this group will work independently to add four numbers (10-60).  They will use any strategy that works for them.  The numbers on these students' worksheets challenge students to regroup into the hundreds place (if students are struggling to regroup into the hundreds place using the traditional column addition strategies, I encourage them to use tens and ones or to use an open number line). 

Group C: Extension

Students in this group will work independently to add four numbers (10-100).  They will use any strategy that works for them.  The numbers on these students' worksheets challenge students to regroup into the hundreds place and to add larger numbers together.  These students will need to have strong addition facts if they choose to solve the problems using column addition. 

Exit Ticket

10 minutes

Now that we have worked together and independently on this skill, I want you to show me what, you know on an exit ticket. 

Allow students to work independently on the exit ticket--if time permits go over the exit ticket at the end of class to check for understanding.