Student Help Card

Lesson 4: Math is Explaining and Sharing5.MD.C.5

Stuck? Start here. Read the steps, try the problem, then check your answer.

I can…

I can construct an argument using equations, drawings, or words, and use volume to defend a recommendation.

Key words

Steps

  1. Suppose each large box is 8 inches long, 3 inches wide, and 10 inches tall. Its volume is 8 × 3 × 10 = 240 cubic inches, so three large boxes hold 240 × 3 = 720 cubic inches.
  2. Suppose each jumbo box is 10 inches long, 4 inches wide, and 10 inches tall. Its volume is 10 × 4 × 10 = 400 cubic inches, so two jumbo boxes hold 400 × 2 = 800 cubic inches.
  3. I recommend buying two jumbo boxes because 800 cubic inches is greater than 720 cubic inches — the total volume is greater, so there is more cereal for the same price.

Try it

Which statement best captures what this lesson means by 'Math is Explaining and Sharing'?

Check your answer

We communicate our reasoning, listen to classmates' arguments, decide whether they are convincing, and check our calculations for accuracy

The summary says it directly: we communicate our reasoning, make conjectures, listen and probe classmates' arguments, communicate precisely, label units accurately, and check that our calculations are accurate.

Sentence starter

I know ___ because ___.

Goal: I can explain my thinking with clear math vocabulary using the words argument, conjecture, and cubic units.