Convert measurement units to solve multi-step problems
Solve multi-step real-world problems that involve converting measurement units to equivalent measurements within a single system of measurement. Example: There are 60 minutes in 1 hour, 24 hours in 1 day and 7 days in 1 week. So, there are 60 × 24 × 7 minutes in one week which is equivalent to 10,080 minutes.
Clarification 1: Within the benchmark, the expectation is not to memorize the conversions.
Clarification 2: Conversions include length, time, volume and capacity represented as whole numbers, fractions and decimals.
Purpose and Instructional Strategies
The purpose of this benchmark is for students to be able to understand the relationship between units of measure through problem solving. This benchmark builds on 4th grade concepts of converting measurement units (MA.4.M.1.2), and becomes a part of a larger context of ratios and rates in Grade 6 (MA.6.AR.3.5).
Instruction should allow students to convert measurements flexibly. For example, when finding the number of inches in 2 yards, students may start with inches, feet or yards when calculating. Classroom discussion should compare those conversions to explore their similarities and differences (MTR.2.1, MTR.4.1).
For students to have a better understanding of the relationships between units, it is important for teachers to allow students to have practice with tools during instruction. This will show students how the number of units relates to the size of the unit. For example, for students to discover converting inches to yards, teachers can have them use 12-inch rulers and yardsticks. This will allow students to see that three of the 12-inch rulers are equivalent to one yardstick (3 × 12 inches = 36 inches; 36 inches = 1 yard), so that students understand that there are 12 inches in 1 foot and 3 feet in 1 yard. Using this knowledge, students will be able to determine whether to multiply or divide when making conversions (MTR.2.1).
When moving into real-world problem solving, it is important to begin with problems that allow for renaming the units to represent the solution before using problems that require renaming to find the solution (MTR.7.1).
Common Misconceptions or Errors
Students confuse renaming units of measurement with the renaming that they do with whole numbers and place value. For example, when subtracting 6 inches from 3 feet, they get 2 feet 4 inches because they think of subtracting 6 inches from 30 inches. Students need to pay attention to the unit of measurement which dictates the renaming (inches in this example) and the number to use (12 inches in a foot instead of 10 inches in a foot).
Instructional Task 1
Zevah is helping her mom plan her sister’s surprise birthday party. Part A. The recipe to make one bowl of punch is shown below. How many cups of punch will they be able to serve at the party if they only make one bowl of punch and there is no punch leftover in the bowl?
Part B. At the party, Zevah wants each balloon to have a string that is 250 centimeters long. The string she wants to buy comes in rolls of 30 meters. How many rolls of string does Zevah need to buy if she plans to have 36 balloons at the party?
Instructional Item 1
Michael is measuring fabric for the costumes of a school play. He needs 11.5 meters of fabric. He has 280 centimeters of fabric. How many more centimeters of fabric does he need?
Instructional Item 2
A recipe requires 24 ounces of milk. Edwin has only a 1/2 cup measuring cup. How many
measuring cups of milk will Edwin need?