Primary Standards:
MAFS.2.MD.1.1 Measure the length of an object to the nearest inch, foot, centimeter, or meter by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes.
MAFS.2.MD.1.2 Describe the inverse relationship between the size of a unit and number of units needed to measure a given object. Example: Suppose the perimeter of a room is lined with one-foot rulers. Now, suppose we want to line it with yardsticks instead or rulers. Will we need more or fewer yardsticks than rulers to do the job? Explain your answer.
MAFS.2.MD.1.3 Estimate lengths using units of inches, feet, yards, centimeters, and meters.
MAFS.2.MD.4.9 Generate measurement data by measuring lengths of several objects to the nearest whole unit, or by making repeated measurements of the same object. Show the measurements by making a line plot, where the horizontal scale is marked off in whole-number units.
Content Knowledge:
Students in 1st grade and kindergarten have worked with using rulers and measuring length with inches. In 2nd grade, students will extend this knowledge to estimating and measuring with inches, feet, centimeters, and meters. Although it is important for students to know how to measure objects, it is equally important they are also able to select appropriate measurement tools, and estimate and measure in appropriate units.
As students explore new measurement units, they develop benchmarks in order to visualize units and estimate lengths using those units. As students gather and observe objects that are one inch long or one foot long, they gain a mental image of the measurement unit and use that image to estimate measurement of other objects.
In this Unit, students will also measure an object twice, each time using different units, e.g. inches & centimeters, or inches & feet. They will then describe how the two measurements relate, for example noticing a pencil that is 6 inches long, may be 10 centimeters long. Through experimentation, students should be able to recognize that when measuring the same object, it would take less of the larger units than it would take of the smaller units. This concept may be difficult for many students, and as a result, students should be provided experiences and activities to predict, then measure, and talk about what they are noticing. It is not the goal of the standard to convert between unit measures.
In 2nd grade, students are introduced to line plots as a way of displaying their measurement data. As students record their measurement data above number lines, they are able to visualize a set of measurements. Seeing both a line plot and a ruler as a number line helps students see the connections between number concepts and models.
GCG 1 – Learning Goal: Estimate and measure length in inches, feet and yards
- Step 1: Estimate and measure lengths to the nearest inch
- Step 2: Estimate and measure lengths to the nearest foot (and yard)
- Step 3: Choose the appropriate customary tool and units to measure an object
GCG 2 – Learning Goal: Estimate and measure length in centimeters and meters
- Step 1: Estimate and measure lengths to the nearest centimeter
- Step 2: Estimate and measure lengths to the nearest meter
- Step 3: Choose the appropriate customary or metric tool and units to measure an object
GCG 3 – Learning Goal: Measure the same object with different units
- Step 1: Measure the same object with two different units
- Step 2: Explain the relationship between the size of the unit and the number of units when measuring length
GCG 4 – Learning Goal: Display data on line plots and analyze that data