# 2.MD.A.3

Estimate lengths using units of inches, feet, centimeters, and meters.

## Summary:

This standard measures a student’s ability to reason through estimating an object’s length based on their previous experience with measuring. This provides students with a real-world context and integrates skills from other areas of math that they have already explored.

## Understanding the Standard:

• Second grade students still need scaffolding in instruction of using measurement tools; introducing the estimation of inches, then feet, then centimeters, then meters is appropriate to students of this age group.
• Using rulers, students should look carefully at how long an inch spans on that measuring tool. From here, students should have the opportunity to make a list of objects in the classroom that they estimate are close to an inch in length.
• This activity can then be expanded to include estimating objects that appear to be a foot, a yard, a centimeter, and a meter in length.
• After listing objects that they estimate in the above categories, students will measure the objects and compare their estimation to the actual measurement (Although this is not required by the standard, it is good practice and builds students' intuition skills).
• The use of a variety of manipulatives and technologies will greatly enhance their exploration of this standard.

## Questions to Focus Instruction:

• Can students find objects that they estimate are reasonably close in length to an inch, foot, yard, centimeter, and meter?
• Can students estimate the lengths of other objects reasonably closely in inches, feet, centimeters, and meters?
• Are my students' estimations reasonable in regard to the actual object length?

## Skills

Prior to: Students have demonstrated their mastery at measuring objects to the nearest inch.