In today’s math talk, students will be exposed to a variety of questions that involve subtracting numbers within 10. The purpose of today’s math talk is to continue to provide opportunities for students to decompose numbers by separating the whole into two parts.
This math prompt has two parts: determining how many peaches are on the tree then determining how many peaches fell off the tree.
Show students the following visual math talk prompt and be prepared to pause the video where indicated:
Then ask students:
How many peaches are on the tree?
How do you know?
Encourage students to turn to their elbow partners or group members and have an open discussion about how many peaches were on the tree and how they could convince someone.
Discuss student strategies of how they knew there were 8 peaches on the tree.
Did they:
- Count each peach?
- Skip count by 2s?
- Subitize smaller amounts? (“I saw 3 peaches at the bottom, then 3 peaches at the side and 2 on the top. So I knew it was 8”)
After students share how many they counted and how they counted them (8 in total), continue playing the video for some of the peaches to fall to the ground.
Then ask students:
How many peaches fell to the ground?
How do you know?
Ask students to share how they determined the amount of peaches that had fallen?
Did they:
- Count back from 8?
- Count on from the 3 remaining peaches that were still on the tree?
Consider discussing the relationship between the subtraction and addition question.
- “How are they the same?”
- “How are they different?”
- “What is another way that the addition question could have been written?” (3 + 5 =8) This is an example of the Commutative property. The order of addends in an addition question does not matter.
Show students the following visual math talk prompt and be prepared to pause the video where indicated:
Then ask students:
How many peaches are on the tree?
How do you know?
After students share how many they counted and how they counted them (10 in total), continue playing the video for some of the peaches to fall to the ground.
Then ask students:
How many peaches fell to the ground?
How do you know?
Again, take this opportunity to make the connection between the addition and subtraction number sentences displayed in the problem.
“How does knowing the addition fact help us with the subtraction fact?”
Addition and subtraction are opposite operations. The understanding of addition facts can help with subtraction facts as the numbers are the same but just in a different order. There is a relationship between 8, 2 and 10.
This may generate a discussion about “fact families”.
Show students the following visual math talk prompt and be prepared to pause the video where indicated:
Then ask students:
How many peaches are on the tree?
How do you know?
After students share how many they counted and how they counted them (9 in total), continue playing the video for some of the peaches to fall to the ground.
Then ask students:
How many peaches fell to the ground?
How do you know?
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