Our Strategies for Adding Four Addends

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Objective

SWBAT regroup using four two-digit addends.

Big Idea

Students identify, use, and share their own strategies for adding four two-digit addends.

Hook

5 minutes

Today we are going to be reviewing adding four numbers together.  In order to get our brains working we are going to do an entrance ticket. (You can also post the entrance ticket on the board and have students work in their math journals instead of printing the worksheet)   When you receive this entrance ticket, begin working on it.  I have put tens and ones blocks as well as cubes on your tables so you can use them if need be.

As students work, I circulate to observe the strategies that they are using.

Entrance Ticket:

At Jade’s Jewelry Store, Jade keeps a table to show how many necklaces she sells every month. How many necklaces did Jade sell in all?

Month

Necklaces Sold

January

41

February

55

March

76

April

38

Introduction to New Material

10 minutes

Please turn to your partner and share your entrance ticket.  Make sure to explain what operation you used, why you used that operation, and what strategy you chose.   

As students share their work, I circulate to hear what strategies students feel most comfortable with/ what strategies are yielding accurate work.  Some students may choose to add the number together in pairs first, some may add two together, then add on the third and then the fourth, others may use tens and ones.

Now  I want two or three students to share their entrance ticket. As your teammates are sharing, I want you to ask yourself : How is their strategy similar to the strategy I used?  How is their strategy different from mine? 

When students share out their answers, I make sure that they are explaining WHY they chose the strategy they did and make sure to highlight the steps that they took to find an accurate answer (procedural errors are very common in these types of problems!!)  

 Depending on time, student mastery, and student engagement you can do another practice problem on the board.  Students can use white boards to do the problem and then can share their strategy with the class. 

Note: Since procedural errors are so common with this type of problem, I spend a lot of time focusing on accuracy and precision (MP6).  I teach some strategies so that students can attend to precision in their work.  These accuracy strategies include checking our work, having a friend check your work, and solving the problem another way to make sure that the work is correct. 

Guided Practice

10 minutes

Now we are going to play an adding numbers game. I have bags that are filled with numbers.  In groups of four, you will each pull out a number.  Then you will work quickly to add these four numbers on your white boards.  Every student in the group needs to be adding up the numbers.  When everyone is done check your work as a team and make sure everyone's answer is accurate.  Students should help each other fix their work if it is not accurate.   The first team to accurately add up all four numbers will get a point.  We will play 4 or 5 rounds. 

 Pre-cut the numbers on the attached sheet and put them in a bag.  Students can sit on the rug or at desks to play.  Make sure that groups are heterogenous and that students are helping each other.

In games like this, students who are more adept sometimes end up simply telling the struggling students how to do the work in attempts to be the first team done.  If this is becoming a problem, I stop "rewarding" students/teams who finish first and instead focus the attention of the game  on working together and explaining our answer clearly.  

 

Independent Practice

10 minutes

Independent practice is tiered based on proficiency with this skill. During the independent practice, I circulate, starting with Group A and then moving to Group B and finally to Group C.  As I circulate, I support students who are struggling by asking guiding questions: (1) Can you show me how you solved the problem, (2) What strategy are you using?  (3) How did you choose that strategy? (4) What steps can you take to make sure your work is accurate? 

Group A (In need of intervention):

Students will add four two digit numbers (10-50).   These students work with smaller numbers and do not need to regroup beyond 100.  Many students in this group are still reliant on concrete materials (cubes, place value blocks, etc.).  

NOTE: In my experience, students in group A will likely struggle during the entrance ticket and introduction to new material given gaps in number sense knowledge. To help them during these sections of the lesson, I provide manipulatives or have them work with a peer buddy.  Working with a peer buddy gives these students a chance to receive coaching from someone other than the teacher.  Additionally, being exposed to more problems that are challenging exposes them to the strategies that their peers are using and pushes their thinking. 

Group B (Right on track!):

 Students will add four two digit numbers (20-60).  These students' problems require them to regroup into the hundreds place.  This group has manipulatives (cubes and tens/ones blocks) available to them. 

 Group C (Extension):

Students will add four two digit numbers (30-100). These students' problems require them to regroup into the hundreds place.  This group has manipualtives available to them as well though in my class, most students solved their problems using a regrouping or tens/ones strategy that did not require them to use manipulatives. 

Exit Ticket

10 minutes

Our thinking job for today was: How can I add four two-digit numbers together accurately?  

What are some strategies that you used to solve these problems? 

Students should be able to recall various strategies including 1) Column addition with regrouping 2) adding two numbers and then adding the sums, and 3) using tens and ones. 

In order to show me what you know, you will take a quick exit ticket.  

When finished, students can swap their exit tickets with a teammate and grade each other's exit ticket as a final reinforcement of the skills.