standard_description: Apply and extend previous understandings of multiplication to multiply a fraction by a whole number.
Grade 4 expectations in this domain are limited to fractions with denominators 2, 3, 4, 5, 6, 8, 10, 12, and 100.
problem_activity: Explain why
$${\frac{1}{2}ab\mathrm{sin}(C)}$$
gives the area of a triangle with sides
$$a$$
and
$$b$$
and included angle
$$C$$
.


aligns: no