standard_description: 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
Look at the title and image of the Newsweek article,
More Than Half of Medical Advice on 'Dr. Oz' Lacks Proof or Contradicts Best Available Science: Study
.
According to this article, a research team looked at 80 pieces of medical advice from
The Dr. Oz Show
and found no evidence to support 43 of these recommendations.
a.   Do you agree or disagree with the claim in the headline based on this information? Why or why not?
b.   Determine whether the following fractions are greater or less than
$$\frac12$$
.
$$\frac{5}{12}$$
$$\frac35$$
Problem 2
a.   Ishmael says that he knows
$$\frac{5}{12}$$
is less than
$$\frac35$$
because
$$\frac{5}{12}$$
is less than
$$\frac12 $$
and
$$\frac35$$
is more than
$$\frac12$$
, so
$$\frac{5}{12}$$
must be less than
$$\frac35$$
. Explain why Ishmael’s reasoning is correct using words or pictures.
b.   Use Ishmael’s strategy to compare the following pairs of fractions. Record your answer with
$$\lt$$
,
$$\gt$$
, or
$$=$$
.
$${{4\over10}}$$
and
$${{5\over8}}$$
$${{7\over12}}$$
and
$${{4\over9}}$$
$${{1\over3}}$$
and
$${{4\over7}}$$
Problem 3
a.   Now Joslyn is comparing
$$\frac46$$
and
$$\frac58$$
. She says that she knows
$$\frac46$$
is more than
$$\frac58$$
because
$$\frac46$$
is
$$\frac16$$
more than
$$\frac12$$
and
$$\frac58$$
is
$$\frac18$$
more than
$$\frac12$$
and
$$\frac16$$
is more than
$$\frac18$$
. Explain why Jocelyn’s reasoning is correct using words or pictures.
b.   Use any strategy to compare the following pairs of fractions. Record your answer with
$$\lt$$
,
$$\gt$$
, or
$$=$$
.
$$\frac{5}{12}$$
and
$${{4\over10}}$$
$${{3\over5}}$$
and
$${{5\over9}}$$
$${{1\over3}}$$
and
$${{3\over7}}$$


aligns: no