The purpose of this activity is for students to solve a story problem with three addends in which two of the addends make 10. Students represent and solve the problem in any way that makes sense to them.

Monitor for and select students with the following approaches to share in the Synthesis:

• Represent addends in the order presented, count all.
• Make a ten by adding 7 and 3 first and then add 8 more (associative property).

The approaches are sequenced from more concrete to more abstract to help students think strategically about the order addends are combined and see how composing a ten can make solving more efficient. Aim to elicit both key mathematical ideas and a variety of student voices, especially students who haven’t shared recently.

During the Activity Synthesis, the teacher records student approaches as drawings on double 10-frames and as equations, so the order of addends in each approach is visible to all students. Consider using three different colors to represent the three addends.

• Invite previously selected students to share in the given order. 
• If students didn’t represent their thinking on 10-frames, record each approach on a double 10-frame and write the equation that matches the order in which the student added.
• Connect students’ approaches by asking:
  • “What is the same about how they solved the problem? What is different?” (They both started with 7. They both added 3 numbers. They both got 18. They are different because the first way added the number of birds in the same order as the story. The other way added 7 and 3 first.)
• Connect students’ approaches to the learning goal by asking:
  • “In each students’ work, where do you see the 3 baby birds?” (In the first way, the 3 baby birds are the last 3 counters drawn on the 10-frames. The baby birds are the last number in the equation, 3. In the other way, the 3 baby birds are the last 3 counters in the first 10-frame. The baby birds are the second number in the equation, 3.”
  • “Why do you think the first student added the 3 last?” (The 3 baby birds are last in the story problem.)
  • “Why do you think the other student added the 3 after 7?” (They started with 7 and wanted to add the 3 to make 10.)

The purpose of this activity is for students to solve more story problems with three addends, in which two of the addends make 10. Students are encouraged to look for addends that have a sum of 10 and think about how that helps when adding (MP7). Students should have access to double 10-frames and connecting cubes or two-color counters to use if they choose.

When recording student thinking, it is important that the teacher write each part of the equation on a separate line. For example, when representing student thinking for record:

• Invite previously identified students to share their work.
• “Who can restate _____’s method?”
• Repeat for each student’s work.
• “What connections do you see between the different methods?” (There are two tens in each method. Each method is addition.)