Comparing Lengths: How Much Longer or Shorter?

Khan Academy

This educational video guides students through solving measurement comparison problems using an interactive digital interface. The narrator demonstrates how to determine the length or width of various geometric shapes (rectangles, lines, triangles) by either reading given labels or using an on-screen ruler. The core focus is on comparing two objects to determine the difference in their sizes, requiring students to perform subtraction and select appropriate comparative vocabulary. The video explores key themes of measurement, subtraction, and comparison. It systematically introduces the concepts of "longer" versus "shorter" and reinforces how to calculate exactly how much larger or smaller one object is compared to another. The problems switch between metric units (meters and centimeters), helping students become comfortable with different scales of measurement while applying basic arithmetic operations to spatial reasoning. For educators, this video serves as an excellent model for thinking aloud through math word problems. It is highly useful for demonstrating the connection between visual measurement and the mathematical operation of subtraction. Teachers can use this to introduce the concept of "difference" in a tangible way, showing that subtraction answers the question of "how many more" or "how many less" units one object possesses compared to another.