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Clarifications
Clarification 1: Instruction emphasizes measuring from the zero point of the ruler. The markings on the ruler indicate the unit of length by marking equal distances with no gaps or overlaps.Clarification 2: When estimating length, the expectation is to give a reasonable number of inches for the length of a given object.
Benchmark Instructional Guide
Connecting Benchmarks/Horizontal Alignment
Terms from the K-12 Glossary
- NA
Vertical Alignment
Previous Benchmarks
Next Benchmarks
Purpose and Instructional Strategies
The purpose of this benchmark is for students to estimate length and formally and accurately measure the length of objects using a ruler. In Kindergarten, students used non-standard units such as paper clips to express the length of objects up to 20 units long (MTR.6.1).- Instruction includes getting students to understand that estimating is about making a reasonable guess. It is not about getting a “right” answer but thinking logically about estimating lengths when thinking about centimeters or inches (MTR.6.1).
- Instruction includes noting that there is a larger number of centimeters for an object than when that object is measured by inches because an inch unit is longer than a centimeter unit (MTR.5.1).
- Estimation of measurement focuses on inches as students may be more familiar with U.S. customary units (MTR.2.1).
Common Misconceptions or Errors
- Some students may not line the zero marking on the ruler to one of the ends of the item being measured. In these cases, students need to explore why lining up at the zero point gives the most accurate measurement and additional practice starting at 0 when measuring.
- Students may measure with the incorrect side of the ruler (i.e., using the centimeter side when needing to measure inches or using inches when needing to measure in centimeters).
Strategies to Support Tiered Instruction
- Instruction includes modeling how to measure an object and guiding students to notice that the objects measurement does not change if the object is placed further down the ruler.
- Modeling includes identifying the end points of an object and lining the end point with the zero mark of the ruler. Note that often the “zero” mark is not labeled and may be the end of the ruler or on the very first tick mark depending on the ruler. State the correct measurement and then as the student watches, move the object down the ruler and ask, “Does the object’s measurement change if its end point lines up with a different number?
- Instruction includes providing opportunities to make and use rulers so that students can construct their understanding of how lengths of each unit align to tick marks and numbers on a ruler.
- For example, students make and use their own ruler in 3 phases:
1. Using paper square tiles glued to a strip of cardstock, students count the units that span an object to measure.
2. Labeling each square tile with a number in the center of the unit, students use numbers to count the units of measure.
3. Students draw tick marks at the end of each unit with a number starting at zero as shown, then eliminate the square tiles. Students then compare this to a ruler to see how the numbers and tick marks correspond to the units of measure (inches). When we use a ruler, we measure the distance from the first to the second endpoint of the object.
- Teacher provides instruction to discuss key differences between centimeters and inches. Write or draw about those differences to use as a reference during instruction.
- For example, a t-chart can be used to organize comparisons about inches and centimeters. Students can use sticky notes to draw pictures and write words or sentences about inches and centimeters.
- Teacher can have students use the inch ruler that they created with only whole inch measurements. Then have students use a modified ruler like the one below with only inch and half-inch tick marks, instead of a ruler with tick marks to sixteenths.
If students continue to confuse inches and centimeters when they are on different sides of the same ruler, they can use two different rulers, one with only inches and one with only centimeters.
Instructional Tasks
Instructional Task 1 (MTR.6.1)
Terri has a tiger plush toy that is 12 inches long. Her sister Kimberley has a smaller version of the same tiger plush toy. What would be a reasonable estimate for Kimberley’s tiger?
Instructional Task 2 (MTR.7.1)
Provide students with several objects to measure, such as a bouncy ball, paper clip, toy car or pencil. Use a table, like the one below to record answers for each part.
Part A. Estimate the length for each object in inches.
Part B. Use a ruler to measure the actual length of each object in inches.
Part C. Find the difference between the actual length and your estimate for each object in inches.
Part D. Measure the same objects in centimeters and record the length of each object in a table like the one below.
Enrichment Task 1 (MTR.7.1)
Extend Instructional Task 2 Part D by having students estimate centimeters before measuring.
Instructional Items
Instructional Item 1
If a reasonable estimate for the length of the broken eraser below is 1 inch, what would be a reasonable estimate in inches for the whole eraser shown?
Instructional Item 2
Kyle was measuring the length of his toy car. He stated his toy car was 4 inches long. Did Kyle measure the length of his toy car correctly? How do you know?
*The strategies, tasks and items included in the B1G-M are examples and should not be considered comprehensive.
Related Courses
Related Access Points
Related Resources
Formative Assessments
Lesson Plans
Original Student Tutorial
MFAS Formative Assessments
Students are asked to explain a method for measuring length and to identify an appropriate tool.
Students are asked to consider the zero point (origin) and end point when measuring the length of objects to the nearest inch.
Students are asked to explain what the marks on a ruler represent and how to use a ruler to measure length.
Original Student Tutorials Mathematics - Grades K-5
Join Inchy the worm and his garden friends for an introduction to the standard unit of an inch. Learn to measure the horizontal length of objects to the nearest inch when given a ruler that is lined up at the zero point in this interactive student tutorial.
Student Resources
Original Student Tutorial
Join Inchy the worm and his garden friends for an introduction to the standard unit of an inch. Learn to measure the horizontal length of objects to the nearest inch when given a ruler that is lined up at the zero point in this interactive student tutorial.
Type: Original Student Tutorial
