Real Live Decimal Number Lines

By: Mary Kienstra on: April 24, 2015  in: number line, place value

Place value with decimals is an abstract concept until kids get in and work with it.  I’ve found that giving kids the opportunity to make real live decimal number lines on the floor and play with the numbers is an engaging way to bring the number line to life.

Decimal place value is new to most third graders.  They have heard the words, but are uncertain as to what a tenth is or how to read 0.1.  Reading 0.001 is even more challenging.  We started with a place value chart and practiced reading these new numbers.

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Students work together to put their number cards in order on the string aka real live decimal number line.

Next, my students made the number cards on 3 x 5 cards following certain directions.  For example, they had to create a card with a number in the thousandths,  another with a number between 0.5 and 1.0, and another with a number less than 0.5.  Then they could create three more cards with any number between 0 and 1.0.  They were so excited about this!  I could have had them cut the number cards out of their books, but having them create their own was much more meaningful for them. It also gave me a chance to informally assess their understanding of what those numbers mean.

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Discussing the numbers and where to place them on the number line is the best part of this lesson.

After the cards were ready, the class split into groups of 4 and gathered around a long length of string stretched across the floor, creating a real live decimal number line.  The discussion was lively as each group labeled the ends of their string with o and 1.0 and then decided what other benchmarks they would need.  Each group added benchmarks at 0.5 and some added each tenth too. They sorted their cards and placed them along the number line, discussing where they should go according to order and magnitude.  The discussion was critical here as they worked together to accomplish their goal, providing instant assistance and feedback to each other.

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Some numbers were so close together that they could not be spread out on the number line. Notice how they are just a little bit different. This group had a system for these.

After all of the groups finished, they took turns presenting their number line to the rest of the class.  Since each student had created his/her own number cards, the number lines all came out different.  Each student had ownership in the project resulting from creating their own cards and placing them along the number line.   The groups were small enough to provide everyone with both practice and support from the group.

We could have practiced this skill on a worksheet, but this lesson was much more engaging by using the real live decimal number line.  Students discussed their ideas and had a small group to give them immediate feedback on where to place the number cards.  Working on the floor, they were active and physically moved their number cards around.  The exit slip at the end of class proved that this was an effective lesson – my students could compare and order decimal numbers after this experience.

Now that we have these decimal number cards, we can use them for practicing rounding as well as for my favorite comparing game, our own version of War, which we call PIECE.

 

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