CCSS.Math.Content.1.MD.A.1
The standard
Order three objects by length; compare the lengths of two objects indirectly by using a third object.
Common Core State Standards for Mathematics · Measurement and Data
What this standard means
Students need to compare object lengths without always using a ruler. They should line objects up at the same starting point, decide which is longer or shorter, and put three objects in order by length. They also need to use a third object as a go-between, such as using a strip of paper to compare two things that cannot be moved together.
Mastery looks like careful aligning, clear language, and correct ordering from shortest to longest or longest to shortest. Students often get stuck when objects are not lined up evenly, when one object is curved or diagonal, or when the comparison tool shifts between measurements.
Ways to teach it
- Give pairs three classroom objects, have them align one end on tape, then order them from shortest to longest.
- Ask students to explain, How can a paper strip help compare two books on different tables?
- Show three pencils of different lengths and ask students to point to the shortest, longest, and middle length.
- Have students compare a shoe, a lunchbox, and a folder to decide which needs the longest shelf space.
Plan a lesson for CCSS.Math.Content.1.MD.A.1
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Related standards
- CCSS.Math.Content.2.MD.A.2
Measure the length of an object twice, using length units of different lengths for the two measurements; describe how the two measurements relate to the size of...
- CCSS.Math.Content.2.MD.A.4
Measure to determine how much longer one object is than another, expressing the length difference in terms of a standard length unit.
- CCSS.Math.Content.1.MD.A
Measure lengths indirectly and by iterating length units.
- CCSS.Math.Content.K.MD.A.2
Directly compare two objects with a measurable attribute in common, to see which object has "more of"/"less of" the attribute, and describe the difference.