There are a lot of children who visit the ice cream stand each week. Most times they sit with their parents at a large picnic table. Jose has collected a few small picnic tables to put near each other for a small “kid’s area.” Mr. Harris loves the idea. Jose gets to work arranging the tables. Jose has four small picnic tables for his kid’s area. He wants to put the tables about 1.5 meters apart. He thinks that this will give the kids plenty of room to not be on top of each other. He puts out the tables and then gets a ruler and a meter stick. Which tool should Jose use to measure the distance between the two tables? If he wants the tables to be 1.5 meters apart, how many meter sticks will the distance actually be? Once Jose gets the tables set up, he wants to design a new placemat for the kids to eat off of. For his placemat, should Jose use a ruler or a meter stick when he measures out the design? Which makes more sense?

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This Concept is all about metric measurement. At the end of the Concept, you will be able to help Jose with his kid’s area.
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### Guidance

Previously we worked on converting different measurements. Now it is time to think about which tools to use to measure different things. We know some metric units for measuring length are millimeters, centimeters, meters and kilometers. Millimeters and centimeters are found on a ruler. There is a meter stick that measures 1 meter. A metric tape measure can be used to measure multiple meters. If you wanted to measure long distances, you could use a kilometer odometer, like in a car, to measure distance.

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What tool should we use when?
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A tool is designed to make measuring simpler. If we have a difficult time choosing an appropriate tool, or choose a tool that isn’t the best choice, it can make measuring very challenging. Let’s think about tools and when we should use them depending on what and/or where we are measuring.

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Here are some general suggestions:
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If the object is very tiny, use a ruler for millimeters.
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If the object is less than 30 cm use a ruler for centimeters.
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If the object is between 30 cm and 5 or so meters use a meter stick.
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If the object is greater than a few meters, use a metric tape measure.
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If the object is a long distance, for instance across town, use a kilometer odometer.
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What about measuring a road race?

A road race is usually a significant distance, so we are going to use a kilometer odometer to measure it.

Now it is time for you to choose an appropriate tool for each measurement situation.

#### Example A

The width of a table

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Solution: A meter stick
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#### Example B

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Solution: Kilometer odometer
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#### Example C

An ant

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Solution: A ruler
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Now that you have worked with the Metric System and tools, let’s go back and look at Jose’s work with the kid’s area. Here is the problem once again.

There are a lot of children who visit the ice cream stand each week. Most times they sit with their parents at a large picnic table. Jose has collected a few small picnic tables to put near each other for a small “kid’s area.” Mr. Harris loves the idea. Jose gets to work arranging the tables. Jose has four small picnic tables for his kid’s area. He wants to put the tables about 1.5 meters apart. He thinks that this will give the kids plenty of room to not be on top of each other. He puts out the tables and then gets a ruler and a meter stick. Which tool should Jose use to measure the distance between the two tables? If he wants the tables to be 1.5 meters apart, how many meter sticks will the distance actually be?

Once Jose gets the tables set up, he wants to design a new placemat for the kids to eat on. For his placemat, should Jose use a ruler or a meter stick when he measures out the design? Which makes more sense?

Now let’s look at the first question. Jose wants to measure a distance that is much longer than a ruler. He could use a ruler, but think about how many centimeters are in one meter. If Jose is wishing to make his work the simplest that it can be, then he should use the meter stick.

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For 1.5 meters, Jose would have to measure out 150 centimeters.
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If Jose uses the meter stick, then he would need to measure one and one-half lengths of the meter stick to have the accurate measurement between the tables.
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For the placemat design, Jose is going to be working with a much smaller area. He can use a ruler for this design since most placemats are about the size of a piece of paper.

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Jose will be able to work well with his ruler while a meter stick would be very difficult to work with.
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### Guided Practice

What would we use to measure the following object?

This object is a paperclip. It is definitely smaller than the length of a ruler, so we can use a ruler to measure it.

### Video Review

James Sousa, Converting Between Metric Units

Other Videos:

- http://www.mathplayground.com/howto_Metric.html – This video expands on the basic information of the metric system. It also begins working with metric conversions.
- http://www.teachertube.com/viewVideo.php?video_id=8896 – The Metric System song to “Arms Wide Open” by Creed this is sung by two science teachers.

### Explore More

Directions: Choose the best tool to measure each item. Use ruler, meter stick, metric tape or kilometric odometer.

1. A paperclip

2. The width of a dime

3. A tall floor lamp

4. The width of a room

5. A road race from start to finish

6. The wing span of a butterfly

7. The wing span of an eagle

8. A shoe size

9. The width of a window

10. The floor space of a tent

11. The distance from the bottom of a mountain to the top

12. The perimeter of a garden

13. The area of a garden

14. The distance from one city to another

15. The size of a fingernail