The Human Number Line

We have begun learning about a new strategy to add and subtract two-digit numbers.  Until now we have been using place value to assist us with these types of questions.  Today we began practicing using the Jump Method.  This method will help us to be able to add and subtract these numbers in our heads.

First we began with the first number in our number sentence.  One student held up this number on a small whiteboard.  We then added a second addend to it.  We looked at how many groups of ten were in that second number.  So for example, if the number was 27, there would be two groups of ten.  We needed a volunteer for each group of ten.  These volunteers would join the number line and hold up all ten fingers.  These students represented our jumps of ten.  We then looked at how many ones were in the number (in our previous example there would be seven ones).  We needed one volunteer to hold up 7 fingers on our number line.  When we were done, we had created a human number line representing our two-digit equation.  We then used our human number line to help us construct a written one.

We repeated the process several times until we were all comfortable using the number line.

We then asked, if we can use this strategy to help with addition, can we use it for subtraction as well.  Yes we can!  So we gave it a try.

Because we were subtracting we had to begin our number line on the other side.  Then instead of adding the groups of ten, we would take them away.

Our next step will be to try to use this strategy to answer questions along side Mrs. Deyoe.  Hopefully with a bit of practice we will be able to comfortably use this strategy with our goal being that students will be able to select the addition/subtraction strategy that makes the most sense to them.

Here are a couple more examples of us practicing the jump method.