Modeling Typical Measurements
If you were to ask a typical 6th grade student to solve the following problem on classroom dimensions in typical United States measurements (i.e inches and yards), you might be surprised at the calculated answer.
Problem: The classroom is 14 feet long and 10 feet wide? Solve the problem showing your mathematical process of the classroom dimensions in inches and in yards.
Student A’s Answer:
- Classroom dimensions = 15 ft. long X 12 ft. wide
- 15 ft X 12 ft = 180 ft.
- 180 ft X 3 yards = 540 yards
The first assumption in solving the problem is to multiply the length of the room by the width of the room to get the dimensions in feet. The calculation for conversion into yards presumes that there are 3 feet in 1 yard and multiplies the solution of #2 by 3 yards to get the solution for #3.
Check out Student B’s answer to the problem:
- 1. Classroom dimensions = 15 ft. long x 12 ft. wide
- (15 ft X 15 ft = 225 ft) by (15 ft. X 12 ft = 180 ft), so final dimension in feet = 225 ft. X 180 ft.
- 15 ft. X 1 yard/3 ft. = 5 yards (feet cancel) by 12 ft. X 1 yard/3 ft. = 4 yards, so final dimension in yards = 5 yd X 4 yds
The room may be odd-shaped, but the calculations are right on. Student B uses the conversion method in #3 and understands the calculation method in #2. Doing metric system conversion is no different. In the next section, typical metric units of measurement will be explored and practiced to show just how easy it is to go from typical measurements to global “metric thinking and conversions.”
Metric System Conversions
Basic units of the metric system are measured in multiples of 10. In testing for student understanding, try asking the students which of the following unit is larger:
- millimeter (mm) or meter (m)
- centimeter (cm) or millimeter (mm)
- kilometer (km) or meter (mm)
If students have no idea how the units compare, you may get a variety of guesses that range from millimeter, millimeter and meter to meter, millimeter, meter. However once you help students understand the prefixes of each unit, they can order them correctly in regard to smallest to largest. You will get life learners who can apply their understanding of this lesson to other subject content areas that use measurements and conversions like temperature conversions and science projects.
Have students get out Webster’s dictionary and look up the prefixes for each metric measurement unit and create a table of the prefix with its numerical answer. For example the chart could look like the following:
- (Prefix) Fraction
- (milli)meter 1/1000
- (centi)meter 1/100
- (kilo)meter 1000
So going back to the questions above, students can start to understand that for #1-meter is largest; #2-centimeter is largest; and #3 kilometer is largest. Students will quickly understand the conversion relationship of using multiplication and division in going from smaller to larger units. Help them practice this understanding by doing a verbal pop quiz to the class asking the following questions:
- How many millimeters are in a centimeter? Answer: Since millimeter is smaller than a centimeter, the student would divide using conversion: 1/1000 mm / 1/100 = 10
- How many meters are in 4 kilometers (km)? Answer: Since kilometer is larger than a meter, the student would multiply using the conversion: 1000 km X 4 km/1 = 4000 meters
Going global with metric and using metric conversions in your metric system lesson plans can be as simple as multiplication and division and using Webster. The real life applications of understanding and being able to apply global metric measurements are huge in understanding the world we live in and measure everyday.