The purpose of this Choral Count is to invite students to practice counting on by tens and notice patterns in the count. These understandings help students develop fluency and will be helpful when students make use of the base-ten structure (MP7).
Launch
“Count by 10, starting at 2.”
Record as students count.
Stop counting and recording at 52.
Activity
“What patterns do you see?”
1–2 minutes: quiet think time
Record responses.
None
Student Response
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Advancing Student Thinking
Activity Synthesis
“Who can restate the pattern in different words?”
“What do you predict would come after 52? Why?”
Activity 1
Standards Alignment
Building On
Addressing
1.OA.A.1
Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.See Glossary, Table 1.
The purpose of this activity is for students to solve a Take From, Result Unknown story problem in which the minuend is a teen number. 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:
Cross off or remove 8 objects from the incomplete 10-frame (last 2 rows of bin) and count the remaining objects.
Cross off or remove 8 objects from the incomplete 10-frame and recognize the remaining objects as 10 and 1.
Know the ten stays the same, and subtract .
The approaches are sequenced from more concrete to more abstract to help students understand different approaches to finding the solution that do not require decomposing a ten. This sequence also helps students begin to notice ways to think about subtracting ones from ones. Aim to elicit both key mathematical ideas and a variety of student voices, especially students who haven’t shared recently.
Representation: Internalize Comprehension. Synthesis: Record students’ approaches on a display and keep it visible during the next activity. Supports accessibility for: ConceptualProcessing, Organization
Launch
Groups of 2
Give students access to double 10-frames and connecting cubes or two-color counters.
Activity
Display and read the Task Statement.
4 minutes: independent work time
“Share your thinking with a partner.”
3 minutes: partner discussion
As you monitor for the approaches listed in the Activity Narrative, consider asking:
“How did you find the answer to the question?”
"How did you decide which game pieces to remove (or subtract)?"
"Where in the picture can you see the game pieces you took away (subtracted)? Where are the pieces that are still in the bin?"
Noah collects game pieces.
He has 19 game pieces arranged like this in his bin.
Noah takes out 8 game pieces to play with.
How many game pieces are left in the bin?
Show your thinking using drawings, numbers, or words.
Student Response
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Activity Synthesis
Invite previously selected students to share in the given order. Record or display their work for all to see.
Connect students’ approaches by asking:
“What is the same about how they solved the problem? What is different?” (They are the same because they all take away 8 from 19. They all got 11. They all took the 8 away from the 9. They are different because one counted to find the answer and the others didn’t.)
Connect students’ approaches to the learning goal by asking:
“What do you notice about how the game pieces are organized?” (They are in two 10-frames. There is a full 10 and 9 more.)
“How did that help you solve the story problem?” (I took away from the 10-frame with only 9 game pieces so that I could keep the full 10-frame.)
“Where do you see a full ten in each students’ work?” (In the drawing, they didn’t cross out any pieces from the full 10-frame —the top 2 rows of the bin. In the other way, they knew 19 is 10 + 9 and they only subtracted from the 9, so there is still a full 10.)
Activity 2
Standards Alignment
Building On
Addressing
1.OA.B.4
Understand subtraction as an unknown-addend problem. For example, subtract by finding the number that makes 10 when added to 8.
The purpose of this activity is for students to find the value that makes the addition and subtraction equations true using methods that make sense to them. Each equation has a total within 20 and one part that is a teen number.
Launch
Groups of 2
Give students access to double 10-frames and connecting cubes or two-colors counters.
Activity
Read the Task Statement.
“You will work on your own at first, then you will share with a partner.”
5 minutes: independent work time
3 minutes: partner discussion
Monitor for students who find the value that makes the equation true by taking away 8 or counting on from 8 to 19 using double 10-frames and counters or drawings. These methods will be discussed in the Lesson Synthesis.
Find the number that makes each equation true.
Be ready to explain your thinking.
Student Response
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Advancing Student Thinking
Activity Synthesis
Display each equation with the unknown value.
Invite students to share how they found each unknown value.
Activity 3
Standards Alignment
Building On
Addressing
1.OA.C.6
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., ); decomposing a number leading to a ten (e.g., ); using the relationship between addition and subtraction (e.g., knowing that , one knows ); and creating equivalent but easier or known sums (e.g., adding by creating the known equivalent ).
The purpose of this activity is for students to learn Stage 5 of the Shake and Spill center. Students use between 11‒20 counters. One partner shakes, spills, and covers up the yellow counters with a cup. The other partner determines how many counters are under the cup and explains how they know. Both partners record the round with an equation.
The recording sheet asks for an expression or an equation. During this stage, students should complete an equation.
MLR8 Discussion Supports. Synthesis: Provide students with the opportunity to rehearse what they will say with a partner before they share with the whole class. Advances: Speaking
Launch
Groups of 2
Give each group a cup, two-color counters, and recording sheets.
“We are going to learn a new way to play the Shake and Spill center. We will play Shake and Spill—Cover with more than 10 counters.”
“First, you and your partner decide how many counters you want to use. You can use 11–20 counters. Then you play the same way we have played in the past. One partner shakes and spills the counters and covers the yellow counters with the cup. Their partner needs to figure out how many yellow counters are under the cup. Then both partners write an equation to match the counters.”
Activity
10 minutes: partner work time
None
Student Response
None
Advancing Student Thinking
Activity Synthesis
Display five red counters and cover ten yellow counters under the cup.
“My partner and I are playing with 15 counters. How many yellow counters are under the cup? How do you know?”
Lesson Synthesis
“Today we added and subtracted with teen numbers.”
Display .
Invite previously identified students to share.
“Which method would you recommend to a friend? Why?” (I would recommend building numbers on 10-frames and taking away because it’s easier to use the counters. I would recommend counting on because it is faster than using counters.)
Standards Alignment
Building On
Addressing
1.NBT.A.1
Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.
If students find a solution other than 11, consider asking:
“How did you solve the problem?”
“How could you use the picture of Noah’s game pieces to show he took out 8 game pieces from his bin?”
1.OA.C.6
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., ); decomposing a number leading to a ten (e.g., ); using the relationship between addition and subtraction (e.g., knowing that , one knows ); and creating equivalent but easier or known sums (e.g., adding by creating the known equivalent ).
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., ); decomposing a number leading to a ten (e.g., ); using the relationship between addition and subtraction (e.g., knowing that , one knows ); and creating equivalent but easier or known sums (e.g., adding by creating the known equivalent ).
Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations , , .
