Teaching Children Linear Measurement

Years ago when I was in the early years of my fifth grade teaching, I thought linear measurement was pretty easy to teach to children. Give them some non-standard units like paper clips, or a ruler, and some things to measure, and they'll usually come up with something close to the right answer. It wasn't until I got my hands on a newish (at the time) resource called Teaching Student-Centered Mathematics, by John Van de Walle that I understood just how many of them didn't truly understand the concept.
http://www.amazon.ca/gp/product/0205408443/ref=as_li_tf_il?ie=UTF8&camp=15121&creative=330641&creativeASIN=0205408443&linkCode=as2&tag=mrsbeatsclas-20
This book quickly became my mathematics Bible. I ditched the textbooks (because I never really believed in them anyway) and started teaching how I knew the students actually developmentally learn.

The activity that sold me on this resource came from the measurement chapter of this resource. It suggested giving the students a broken or unnumbered ruler and having them measure an object to truly gauge whether they understand how to use a ruler or not. Let me tell you... I was BLOWN AWAY. I took an old wooden ruler and broke the zero end off. When I handed it to each of my students in a one-on-one conference, easily half of them couldn't do it! The looks on their faces were priceless, really. Many of them lined the object up where they thought the zero might have been. Others lined it up with the first full line and measured from there, not taking into account that the number wasn't zero. Still others simply told me it wasn't possible to measure the object since the zero was gone. Those who came closest lined the object up to the ruler and then proceeded to count the lines, ending up with a measurement that was one unit too high.

What this activity taught me was that students learning about using a ruler needed to understand that it was the spaces, not the lines, on the ruler that they were really counting when measuring something. By the time they got to me in fifth grade it was often too late - they had those habits already. Well... now I've got them early! :)

Today in my grade 2/3 classroom we explored unnumbered rulers. First we highlighted the parts of the ruler on a worksheet: the first line (where we typically begin measuring from), the measuring edge (vs the opposite side of the ruler), and then we added smiley faces in the spaces between the lines - to really focus our attention on the spaces - and after this they did some measuring for me. Every single one of them got it!
I can't wait to move into using standard rulers to truly see if the kids can transfer this newfound understanding!

4 comments

  1. I love Van de Walle books. I use the broken rulers with my 4th graders too. One year, I bought a bunch of rulers at then beginning of school when they were running them on sale. I brought them home and started breaking the ends off. My son thought I had lost my mind.
    Brooke
    Tales from a Fourth Grade MathNut

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    1. Haha! I can imagine! I love the looks on the kids' faces when I first hand it to them! :) Thanks for stopping by, Brooke!

      ~Erin

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  2. Thanks for sharing this! I will always begin with the unnumbered rulers from now on! I'm your newest follower!

    :) Ash
    The Rolly Chair

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    Replies
    1. I'm glad you got some inspiration from this post, Ash! Thanks for stopping by, and for following! :)

      ~Erin
      Mrs. Beattie's Classroom

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