I love the math that we teach in junior high. Honestly, I was made to be a middle school math teacher. The topics that we teach came easy to me the first time around, and I’ve spent a lot of time figure out how to break things down for students. That is why I love this standard of using triangles to teach slope. It breaks down what slope is and uses something like triangles that students are already familar with. Some years we haven’t given this standard the attention it deserves because of time, but when we do take the time, it really helps students understand slope better.
Teaching slope using similar triangles in an interactive notebook
Using the interactive notebook and graphic organizers helps build students’ background knowledge and creates a reference to use as they learn. In my class we have 5 basic components for every unit of notes which give students a variety of visuals and interactive experiences to remember the topic. I’m going to show you what the components look like in my interactive notebook for slope and similar triangles. In this post you’ll get a complete picture of how I break this whole topic down for students in the interactive notebook.
I can statements
One way to gives student access to the objectives that we’re learning is through student-friendly I can statements. I include them in every unit that we study. For this topic, I’ve included 5 I can statements on this list:
- I can graph a line from an equation in slope intercept form.
- List the characteristics of similar triangles.
- I can identify if two triangles are similar.
- Find the slope of a line by drawing a triangle and finding rise over run.
- I can use similar triangles on a line to explain why the slope is the same everywhere on a line.
Students have an opportunity to really get a strong foundation for all things slope by learning about these similar triangles. They also get to build on the work they did in 7th grade with proportions and bring it full circle. As you can see, there are a few discrete skills here that will give them a leg up throughout their interactions with slope in all its forms.
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Building background
Often times the best way to build background is to focus on vocabulary. This topic has a fair amount of vocabulary, so the background building activity that we do is called Odd One Out. Students are given three words and they have to circle the one that doesn’t belong and then explain why. This activity works great and gets kids talking and writing about some words they’ll use a lot during the unit.
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A variety of graphic organizers
Graphing slope foldable notes
For this topic, students have a series of graphic organizers that we add to the notebook. First, we start with the Graphing Slope Foldable Notes. This set of notes gives students a list of the steps for graphing a line from an equation using a series of triangles.
I’ve learned that if you want students to know how to use their notes, then you have to model it over and over. If you put this in the notebook one time and never refer to it as the teacher, then many students don’t think to go back and use it. So, after discussing and adding this page to the notes, I make sure that during the many opportunities to graph lines throughout the year, we go back to this foldable. This way, they use it over and over again and are reminded of how to graph slope from an equation.
Similar triangles and slope foldable
This foldable gets down to the nitty gritty of this topic. It breaks this topic down to three things.
- What are similar triangles?
- How to find slope using a triangle.
- How similar triangles and slope work together.
By using this foldable, students can see at a very basic level how this all works together. It gives them another way of looking at slope. Also, they’re synthesizing slope with the concepts of triangles and proportions which they’ve worked with for a long time.
The derivation of the y=mx + b formula foldable
Part of understanding slope is being able to derive the slope intercept formula. This foldable gives students just that chance. You have students draw different lines and then put the points on the tables on the outside of the foldable. Then, they can derive the formulas with a variety of lines.
This isn’t an introductory activity. Students get a chance to explain why this formula works. This requires that they already have basic comfort level with slope when you use this foldable.
Finding the slope between two points foldable
Students tend to struggle a little bit with coordinate points that aren’t on a graph. It’s an abstract concept for them. I like to use foldables like this one to help students remember this process. On the inside of the foldable, students get to see step by step examples of how the formula works. Also, there are some practice problems for them to do on their own, or if you need to do more modeling then you can do that too.
Let’s work it out with slope and similar triangles
At some point during the note-taking process it’s time to do some more practice problems with students. That’s why I’ve added these guided practice problems to our notes. It’s so nice to have problems already to go in students’ notes when I need them. I use these guided problems differently depdending on the situation. Sometimes we do them all together, and other times I skip one or two of them. I put them in students’ notebooks because then we can refer back to them when needed. These practice problems give students a few different ways to see this topic in action.
Putting it all together
I hope this has helped you see how you can use an interactive notebook to teach similar triangles and slope. Remember that every situation is different, and that you don’t have to use everything in this post. Also, you may find that one of the foldable above actually works better for you in a different unit. You just have to use your best professional judgement as a teacher.
At the end of this unit’s notes, students will have a great reference to go back to in their interactive notebooks. At the end of the unit we always go back to the I can statements and reflect on them. This provides students a great chance to evaluate how they did during their notes and practice for all 5 learning objectives. This final step is a powerful part of the learning process.
Use the ideas above to bump up your interactive notes, or you can grab the entire set of notes I use in my classroom in the Similar Triangles and Slope Interactive Notebook Pack. For practice ideas for all things slope, be sure to check out 11 Activities that Make Identifying Slope Easy.
Thanks so much for reading! Until next time.
