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## PowerPoint Slideshow about ' Children’s Thinking Activity Part 1' - ariel-gross

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Children’s Thinking Activity Part 1

- 1A. Do you see 5 boxes each with 7 turtles?

Children’s Thinking Activity 1

- 1B. Do you see 5, 10, 15, 20, 25, and then 10 more?

Children’s Thinking Activity 1

- 1C.
- Can you see 5 • 5 + 2 • 5?

Children’s Thinking Activity Part 1

- 2A. Do you see 12 bags with 6 candies in each?

Children’s Thinking Activity Part 1

- 2B. Do you see 10 bags, with 60, and then 2 more bags 2 • 6 = 12?

Children’s Thinking Activity Part 1

- 2C Can you see 10 • 6 + 2 • 6?

What skills and concepts did these students know?

- BASIC MULTIPLICATION FACTS!
- And… (give examples for each)

Link the pictorial models

- Suppose I want to multiply 3 • 4.

Link the pictorial models

- Suppose I want to multiply 3 • 40.
- This is much harder to draw, but it can be done.

3

Link the pictorial models- As the numbers get bigger, it is harder to draw in all the little dots. But the area model will work well: 3 • 40:

7

Rectangular Area Model- Let’s look a little closer:

Let this be a unit square--that is, a square that measures 1 unit on each side.

Then, this is a representation for 7 • 15.

Rectangular Model

- You try: 46 • 23 Use the base 10 blocks or draw a picture.
- Now, can you explain where these products are in the diagram?

46 • 23 = (46 • 20) + (46 • 3) or

= (23 • 40) + (23 • 6)

Compare models

- Can you explain how this is related to the lattice multiplication model you did for Exploration 3.13?
- Can you explain how this rectangular model is related to the standard multiplication algorithm?
- Can you explain how this rectangular model is related to the four students’ models?

Multiplication-the area model

- How could Jemea’s strategy be represented using the rectangular area model?

Jemea

30 • 12 - 12

Thomas

17 • 36 = ((17 • 10) • 3)+ (6 • 10) + (6 • 7)

Explain why…

- Can you show, using pictures or base-10 blocks, why 3 • 14 = 14 • 3?
- Can you show or explain why? Give a reason? Draw a picture?
- 2 • (3 • 14) = (2 • 3) • 14?
- 2 • (3 • 14) = (3 • 2) • 14?
- 2 • (3 • 14) = 3 • (2 • 14)
- 2 • (3 • 14) = 14 • (2 • 3)
- 2 • (3 • 14) = 3 • 14 + 3 • 14
- 2 • (3 • 14) ≠ 2 • 3 + 2 • 14

46 46X 37X 37 42 42 280

46X 37 2842

What is 280?

Is it 7 • 4 or 7 • 40?

What does the placeholder mean?

Where is the error?

46 46X 37X 37 42 42 280

46X 37 2842

What is 280?

Is it 7 • 4 or 7 • 40?

What does the placeholder mean?

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