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Converting Metric Measurement in Word Problems
Students will be able to solve multi-step word problems that require converting metric units (involving whole numbers and decimals).
- Pass out metric rulers, one per student.
- Direct students to examine their rulers and note the size of the different units.
- Prompt students to share with a partner the names for any units they know (like centimeters and millimeters) and examples of items they could measure with those units.
- Pose the following question to your class: "How might you measure something using the metric system that is longer than a ruler, like their desk, the height of the door, or the distance to the grocery store?"
Explicit Instruction/Teacher modeling(10 minutes)
- Direct students to think about our money system and how the units are related. Draw a chart on the board, from right to left with the headings: "100 dollars," "10 dollars," "1 dollar," "one dime," and "one penny" across the top. Under each heading, in the first row, draw and name the coin or bill used for each. Then start a new row and write the value of a dollar (1 penny = .01 dollar; 1 dime = .10 dollar; etc.).
- Note how each value is related to the ones to the right and left of it. Point out that it is 1/10 of the value to the left and 10 times the value of the one to its right. Define this kind of a system as a Base tenSystem.
- Explain that the metric system is also a base ten system, just like our money system. Rather than the unit being a dollar, the metric system uses meters, grams, or liters.
Guided practise(20 minutes)
- Distribute a copy of the Preparing to Convert Metric Measurement Using Deconstruction worksheet to each student. Review the chart at the top of the page. This sheet will help students think about the different metric units and how they are related.
- Have students work in pairs or small groups to collaborate on Part A. Encourage your class to discuss and explore, and use rulers to assist them.
- Review answers to Part A and discuss as needed.
- Now, go over the example in Part B and model how the measurement is converted from centimeters to meters using deconstruction (they look like number bonds).
- Instruct students to use the model as a guide and try number 3 on their own.
- Review and discuss.
Independent working time(20 minutes)
- Give students about 15 minutes to work through example number 4.
- Review and discuss the solution. Ask students if they have discovered any other ways to convert metric units. Do they have any shortcuts?
- Show students the method of moving the decimal using the chart on the page. Locate the original units and the units the value is to be converted into on the grid. Note how many units you move from one to the other, and in which direction. This tells you how far to move the decimal and in what direction.
- Distribute the Metric Length Measurement: Word Problems worksheet for students to independently practise converting measurements.
- View the short instructional videos in the list of supplemental media at the end of this lesson.
- Do some of the Metric Length Measurement problems as a class or small group before independent practise, modeling the movement of the decimal.
- Have students research to determine what units in the metric system are smaller and larger than the units discussed in class (micro, nano, pico, mega, giga, tera, etc.).
- Have students convert other metric measurements like mass and volume in the Metric Mass and Volume Measurement in Word Problems practise sheet.
- Write a metric conversion problem on the board. Have students solve it and write their solution on a scratch paper at their seat. Then you can quickly circulate to check answers. Students who get it wrong should be encouraged to try again. Students who get it right should create a problem of their own and trade with a friend.
Review and closing(10 minutes)
- Discuss the "Questions for Discussion" at the end of the Preparing to Convert Metric Measurement Using Deconstruction worksheet.