1.MD.A.2

Express the length of an object as a whole number of length units, by laying multiple copies of a shorter object (the length unit) end to end; understand that the length measurement of an object is the number of same-size length units that span it with no gaps or overlaps. Limit to contexts where the object being measured is spanned by a whole number of length units with no gaps or overlaps.

Summary:

This standard focuses on the student’s ability to understand the concept of measuring the length of an object from end to end using  objects. The student will measure lengths which are a whole number of length units, where the length unit is some shorter object (e.g., using paper clips, unifix cubes, chain links, etc). Students need to have a wide variety of experiences with hands-on activities that allow them to manipulate the objects being measured.

Understanding the Standard:

• Use non-standard measuring tools (e.g., paper clips) to begin the inquiry into measurement. Students should understand that an object's length is determined by the number of measuring units (in this case paper clips) that stretch from end to end on the object that is being measured.
• Allow students to work hands-on with rulers, drawing their attention to the whole number representation of the object used for measuring. Their experiences should extend beyond measuring lines on a piece of paper, and instead should extend to objects they encounter in their day-to-day experiences in the classroom and beyond.
• Extend the experience to include exploration into the number of smaller objects that are necessary to make a larger object, reinforcing the part-whole relationship theme which is repeated quite often throughout mathematics.

Questions to Focus Instruction:

• How do I know my students understand that length is measurement of an object from one end to another?
• Are my students accurately measuring an object?
• Are there gaps between the objects or are they overlapping?
• Have my students begun measuring at the starting point and ended measuring at the end point of the object?
• What objects whose lengths are a whole number multiple of the length of a reference object can be provided to students ?
• Are students able to use a reference object to correctly measure the length of a larger object, by placing copies of the reference object end-to-end with no overlap and no gaps?
• What activities and opportunities can I provide that will allow students practice with using smaller objects to measure the length of a larger object?
• How can I use manipulatives and other technologies that will allow for direct, hands-on exploration of measuring the length of objects?

Skills

Prior to: Students can make comparisons between two and three objects using comparison words such as long, longer, longest; short, shorter, shortest; tall, taller, tallest; and small, smaller, smallest. They can use positional words to communicate the position of objects.