The purpose of this activity is for students to measure lengths using a ruler that is marked with half inches and quarter inches. Building on their understanding of equivalent fractions, students recognize that lengths that line up with a half-inch mark can be read as one-half of an inch or two-fourths of an inch. They also recognize that lengths that are whole numbers of inches can be expressed as fractions.

• “In the image for the first problem, how is the ruler lined up to the worm?”
• “Why doesn't it make sense to line up the left end of the ruler with the left end of the worm?”

• Invite students to share how they recorded their measurements and why they chose to record them in the way they did.
• “Let’s think more about the first worm you measured. What are all the ways that we could record its length?” (4 inches,  inches,  inches)
• “What are all the ways that we could record the length of the last worm?” ( inches,  inches,  inches,  inches)
• “We can use different numbers to describe the same length because the numbers are equivalent.”

The purpose of this activity is for students to practice measuring with a ruler that is marked with halves and fourths of an inch, as well as to identify lengths that can be described in different ways because they are equivalent. This activity gives students an opportunity to attend to the details of each measurement and to use language precisely (MP6). Students are prompted to find objects with whole-number lengths and those with fractional lengths. The work here allows students to reinforce earlier work on expressing whole numbers as fractions and naming equivalent fractions.     

• “Discuss with your partner how you used equivalent fractions as you measured lengths today.” (The ruler is marked with half inches and quarter inches. I knew that the mark for was also the mark for .)
• “Since some of the marks on the ruler can be described with halves or fourths, how did you decide which way to describe the lengths you measured?” (If the end of the object landed right on one of the half marks, we described it as a half. If it landed in between the half marks, we used fourths to describe the length.)
• Select previously identified students to share the equivalent lengths they wrote.
• If no students express whole numbers as fractions, ask: “Could 7 inches be expressed in another way? How many half inches is that? How many quarter inches?”