Volume of Prism Drawings
10 min
Narrative
The purpose of this Number Talk is for students to multiply three factors. Strategies for multiplying three factors will be helpful as students find the volume of a rectangular prism in this lesson and upcoming lessons. Since the first problem has only two factors, it is not important to gather multiple strategies in order to leave more time for the other problems. Students may connect the third factor in the final three problems to “adding another layer of cubes” in a prism when finding volume. Invite these students to share their observations during the Activity Synthesis.
This is the first time students experience the Number Talk routine in grade 5. Students are familiar with this routine from a previous grade, however, they may benefit from a brief review of the steps involved.
Launch
- Display the first expression.
- “Give me a signal when you have an answer and can explain how you got it.”
- 1 minute: individual think time
Teacher Instructions
- Record answers and strategies.
- Keep expressions and work displayed.
- Repeat with each expression
Student Task
Find the value of each expression mentally.
- 6×4
- 3×2×4
- 3×2×5
- 3×2×6
Sample Response
- 24: I know 6×2=12 and 12×2=24.
- 24: It is equal to the first expression, but instead of 6, it has 3×2.
- 30: I know 6×5=30.
- 36: I just added another 3×2 or 6, 6×6=36.
Activity Synthesis (Teacher Notes)
- “How did changing one of the factors impact the product?” (Increasing one of the factors made the product greater by 6.)
- Consider asking:
- “How are the last three expressions like the work we did with prisms yesterday?”
- “Who can restate _______’s reasoning in a different way?”
- “Did anyone have the same strategy but would explain it differently?”
Standards
- 3.OA.7·Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that 8 × 5 = 40, one knows 40 ÷ 5 = 8) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
- 3.OA.C.7·Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that <span class="math">\(8 \times 5 = 40\)</span>, one knows <span class="math">\(40 \div 5 = 8\)</span>) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
- 5.MD.5·Relate volume to the operations of multiplication and addition and solve real world and mathematical problems involving volume.
- 5.MD.C.5·Relate volume to the operations of multiplication and addition and solve real world and mathematical problems involving volume.
20 min
15 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Volume of Prism Drawings
10 min
Narrative
The purpose of this Number Talk is for students to multiply three factors. Strategies for multiplying three factors will be helpful as students find the volume of a rectangular prism in this lesson and upcoming lessons. Since the first problem has only two factors, it is not important to gather multiple strategies in order to leave more time for the other problems. Students may connect the third factor in the final three problems to “adding another layer of cubes” in a prism when finding volume. Invite these students to share their observations during the Activity Synthesis.
This is the first time students experience the Number Talk routine in grade 5. Students are familiar with this routine from a previous grade, however, they may benefit from a brief review of the steps involved.
Launch
- Display the first expression.
- “Give me a signal when you have an answer and can explain how you got it.”
- 1 minute: individual think time
Teacher Instructions
- Record answers and strategies.
- Keep expressions and work displayed.
- Repeat with each expression
Student Task
Find the value of each expression mentally.
- 6×4
- 3×2×4
- 3×2×5
- 3×2×6
Sample Response
- 24: I know 6×2=12 and 12×2=24.
- 24: It is equal to the first expression, but instead of 6, it has 3×2.
- 30: I know 6×5=30.
- 36: I just added another 3×2 or 6, 6×6=36.
Activity Synthesis (Teacher Notes)
- “How did changing one of the factors impact the product?” (Increasing one of the factors made the product greater by 6.)
- Consider asking:
- “How are the last three expressions like the work we did with prisms yesterday?”
- “Who can restate _______’s reasoning in a different way?”
- “Did anyone have the same strategy but would explain it differently?”
Standards
- 3.OA.7·Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that 8 × 5 = 40, one knows 40 ÷ 5 = 8) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
- 3.OA.C.7·Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that <span class="math">\(8 \times 5 = 40\)</span>, one knows <span class="math">\(40 \div 5 = 8\)</span>) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
- 5.MD.5·Relate volume to the operations of multiplication and addition and solve real world and mathematical problems involving volume.
- 5.MD.C.5·Relate volume to the operations of multiplication and addition and solve real world and mathematical problems involving volume.