options: Apply and extend previous understandings of multiplication to multiply a fraction or whole number by a fraction.

Solve real world problems involving multiplication of fractions and mixed numbers, e.g., by using visual fraction models or equations to represent the problem.

Apply and extend previous understandings of division to divide unit fractions by whole numbers and whole numbers by unit fractions. (Students able to multiply fractions in general can develop strategies to divide fractions in general, by reasoning about the relationship between multiplication and division. But division of a fraction by a fraction is not a requirement at this grade.)

Interpret a fraction as division of the numerator by the denominator (a/b = a ÷ b). Solve word problems involving division of whole numbers leading to answers in the form of fractions or mixed numbers, e.g., by using visual fraction models or equations to represent the problem. For example, interpret 3/4 as the result of dividing 3 by 4, noting that 3/4 multiplied by 4 equals 3, and that when 3 wholes are shared equally among 4 people each person has a share of size 3/4. If 9 people want to share a 50-pound sack of rice equally by weight, how many pounds of rice should each person get? Between what two whole numbers does your answer lie?

Interpret multiplication as scaling (resizing), by:
- Explaining why multiplying a given number by a fraction greater than 1 results in a product greater than the given number (recognizing multiplication by whole numbers greater than 1 as a familiar case); explaining why multiplying a given number by a fraction less than 1 results in a product smaller than the given number; and relating the principle of fraction equivalence a/b = (n×a)/(n×b) to the effect of multiplying a/b by 1.
- Comparing the size of a product to the size of one factor on the basis of the size of the other factor, without performing the indicated multiplication.
problem_activity: Problem 1
Act 1: Watch the following video –
The Big Pad (Act: 1)
a.   What do you notice? What do you wonder?
b.   What is the area, in square centimeters, of the big pad? Make an estimate.
Problem 2
Act 2: Use the following information to solve -
The small pad is a square with a length of
$$7\frac{3}{5}$$
cm.
The big pad is also a square and has a length equal to
$$3\frac{2}{3}$$
small pads.
Problem 3
Act 3: Reveal the answer -
The area of the big pad is
$$776\frac{124}{225}$$
square centimeters. Was your answer reasonable? Why or why not?
Problem 4
Act 4 (the sequel): Look at the following image of the dimensions mentioned on the big pad -
[IMG]
Do these dimensions result in the same area as what we computed in Anchor Task #3? Why or why not?


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