Using A Clothesline for Slope

This is quite a few weeks overdue, but I saw Jon Orr’s twitter and blog post about using the clothesline to do a slope activity. I ran mine (files at the end of the post) much like he did, but with a few modifications. He does a great job sharing all the background thought that went into designing the activity so its worth checking out.

Here is a basic run down of what we did. I had two pieces of yarn taped up which ran the width of my classroom. Kids entered and were immediately curious and ready to start.

Each student got a pair of two points and was asked to calculate slope. They wrote the slope on the card and then would go up and add it to the number line. I used no anchors at first, instead letting students adjust others as needed to fit their card on correctly. This brought out some great student to student dialog when both trying to place cards. I had more cards than students, so they’d grab a few card and repeat until all the pairs were placed on the line. One of the cards had an undefined slope.  We had a quick whole group discussion on where to put it. They decided to set it on a cart off to the side.

When the point stack was exhausted, they each took a graph card and drew a graph of a line using the two points. I had them place the graph on a second number line over the corresponding points. Rinse and repeat until all had a graph.

Each student walked along the line as was asked to jot down what they noticed, what they wondered with each line and the connection between the two number lines.  Again, I had them think about the graph of the undefined slope and where it looked like it would fit. They shared out their notices and wonders with a small group and any lingering questions were brought up to the whole class.

Finally, each student a blank card and graph and had to create their own ordered pair and graph to place on the line that would lie in between two assigned points on the graph that were currently right next to each other. I actually  let them pick the two points, but the key is to pick a target interval first, not create some points and see where it fits. For students that needed more support I was able to quietly suggest intervals that they would have more success with. Another way to make it their own, they could keep the (0,2) as a point or try to find two points where (0,2) was not a point, or do both. 

Overall, it was a fun way to practice the slope between two points and reinforce the visual picture of changing slope.  I noticed fewer errors between a slope of 0 and an undefined slope after the activity, and we had the bonus of some number sense practice when trying to figure out how far apart of place cards and readjust them as we added numbers. It would have been quicker to provide anchors, but they extra few minutes was worth it to see the thought process and conversations.

Here are my files for Clothesline Points and the one for the Clothesline Graphs that I used. my class is small, so I had 15 of each card, plus the blanks for the end activity. It would be easy to add a more points as needed for a larger class. Nothing too fancy, but it did the trick.

 

 

 

 

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Author:

I am a math teacher at a public, alternative high school school. I’m the only math teacher at my site, so I get to teach it all. This is good. The bad? I have 7 different preps! Twitter: @altmath

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