Lesson 3: Math is In My World5.NBT.B.7

I can…

I can represent a real-world situation with a tape diagram or table and use decimal operations to solve it.

Key words

• representation — A picture, diagram, table, or equation that shows the mathematics in a situation.
• tape diagram — A rectangle cut into equal parts that helps you visualize how a total breaks apart.
• tool — Anything you choose to help you see relationships and solve a problem — a table, a diagram, a graph.
• ordered pair — Two numbers that go together, like a time and a number of trips, that you can plot as a point.
• round trip — A complete journey from the start, to the destination, and back to the start.

Steps

1. A pile of coins is too big to count one at a time. About how many coins are in the pile?
2. I do not count every coin — I find a small stack I CAN count, about 10 coins.
3. Then I estimate how many stacks like that are in the pile. I count about 15.
4. 15 stacks of about 10 is 15 × 10 = 150, so my estimate is about 150 coins — reasoned, not random.

Try it

Lena is planning snacks and drinks for her soccer team's end-of-season party. Which way of working best matches the idea that math is in our world?

Check your answer

Picture the party, use a table or diagram to show how the amounts connect, and choose the tool that fits best

Math in our world means picturing a real situation, using tools to show how the amounts are related, and choosing the tool that fits the problem.

Sentence starter

I know ___ because ___.

Goal: I can describe my tool using the words tape diagram, table, and this represents ___ .