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Second Grade Math: How To Read a Ruler

By Kathy Foust

All items on a ruler can be daunting to young learners. This activity lets students use a hands on method that is fun and educational

Introduction to Rulers

By now you may have already done the previous lesson plans in this series (see the links below). If so, your students have seen you use a ruler and have been introduced to how to use a ruler. Now it's time to get more detailed about rulers and similar instruments. For this lesson plan you will need the items listed below.

  • Ruler
  • Folding Yard Stick
  • Tape measure

This lesson is based in part on how information is processed in our brains. Americans are still using the ruler as a standard tool of measurement because whether we realize it or not, it is easier for us to imagine the units because they are based on our bodies, where the metric system was once based on the distance from the earth to the sun. I don't know about you, but that's a measurement I can't easily wrap my mind around and I don't expect my students to be able to either.

Explain the history of measuring tools. Let them know that a foot is based on the size of a man's foot, so that when there were no measuring tools available, a man could walk toe to toe across an area to get a measurement. A yard is based on the space between the average man's normal footsteps. Display this with the ruler and the yardstick. Of course, the measurements may not be exact, but it gives your students a good visual concept. As a point of interest, let them know that horses still today are measured in hands. explain this concept to your students, but don't focus too long on it.

Display the 3 types of measuring tools you have. Explain applications for each one. Take measurements around the classroom of various objects to demonstrate the use. When measuring, write on the board what the class estimates something to measure. Keep it simple. Start off with estimate measurements. This means you may measure a book and say it is about a foot long. Then, get more precise.

Write the phrase "out of 16" on the board. When you measure something and you come up with say 2 3/4 inches, write the number 2 above the "out of 16". Next, write 9 in front of the out of sixteen. You should be measuring with the students and counting the notches on the ruler or other measuring tool so that students can understand how you came up with this number.

It's best to not reduce the fraction unless you have already gone over that material with your students. Or, if you want the reduced number, then count with the students the size line corresponding with that number. For 3/4, you should have the students focus on counting the larger lines that correspond with the division of four on the ruler.

Have the students think of 3 items in their home that they can measure with a ruler. Write them down. Have students write down what they think the item measures, then go home and measure the items with a ruler.