PowerPoint created by Parsheena Berch Resource : JBHM material Pictures: Google Images

Estimating and Measuring

Estimate and measure length to nearest millimeter in the metric system and one- sixteenth inch in the English system. Remember, yesterday we learned how to measure things with a ruler. Inches are evenly divided into fractional parts to ensure an accurate measure. We use measurements for many things such as for how tall someone is. We will focus on measuring using the metric side of the ruler today.

Metric Measurement: Examine the metric side of the ruler to determine how it is divided. The markings that show millimeters are small and the markings that are bigger are the centimeters. The meter is the basic unit of length in the metric system. Remember that the millimeter (mm), the centimeter (cm), and the kilometer (km) are also used to measure length in the metric system.

How many millimeters are in a centimeter? (10) The same is true with metric measurement as with English measurement. The smaller the units of division on the ruler, the more accurate a measurement will be. When using the metric side of the ruler, we will always measure to the nearest millimeter in this lesson.

Handout #1

Additional Examples: 1) Draw a segment that is 3 ½ inches long. 2) Draw a segment that is 121 mm long.

Estimating Measurements “I need to get an estimate for the height of this doorway. I know that height means how tall it is, so I am estimating how far it is from the floor to the top of the door. That is taller than me, so I will at least be using feet to measure. I could probably use yards since it is more than three feet—I know that because I am more than three feet tall. Since yards are similar to meters, I could also estimate it in meters. Now, as I said, I know it has to be tall enough that most people can walk through it. Many people are as much as six feet tall. This would be about two yards or two meters. Three yards or three meters would be like nine or ten feet, that would be quite a bit taller than this door. So, I would estimate this door to be about two yards or two meters long.”

Working in pairs, choose ten objects in the classroom. Record an estimated measurement (both English and metric). Then measure the length of the object and record the exact measurement (both English and metric).

Closure: List – List what you already knew about measuring length. Learn – What else did you learn about measuring length during the last two class sessions? Link – How can you link what you learned during this lesson about measuring length to everyday life?