I have taught equations of parallel and perpendicular lines in Geometry during the Coordinate Geometry Unit and in Algebra 1 in the Linear Functions Unit.
Wherever you’re tasked with teaching it, here are some ideas for making it better for you and your classes!
Discovering Parallel Slopes-Technology Connected
I LOVE this Desmos activity! It’s very interactive for students. They try to just eyeball creating parallel lines…and the activity shows exactly how many degrees OFF their attempt is.😆
The activity continues, guiding students toward better understanding. It’s one of the best I’ve seen for its interactiveness (just made that word up) and unique way of allowing students to get feedback on their specific responses.
Discovering Perpendicular Slopes-Technology Connected
Here’s a simple, yet effective desmos slider for understanding the slopes of perpendicular lines.
I’ve created a Google Slides activity for you so that you can extend the learning into more of a discovery activity with your students. For me, this is one I’d especially take the time to do in an Algebra 1 Support or Geometry Support (yearlong instead of semester long) class.
It’s perfect as a partner activity, as one student can pull up the desmos on their device and the partner can pull up the Google Slides on theirs.
Here are more of the slides in the activity.
Discovery Activity-Paper & Pencil
This is a great activity from Math Giraffe if you have time (our most valuable classroom resource)…and it’s free to download!
My favorite sound in the classroom is the “Oh! I get it!” noises you hear when the proverbial lightbulb comes on. This is one of those activities that encourages this sound.
When students can tell you what pattern they’re seeing, it’s a good day.
Choose Your Method for Solving
Personally, I’ve always taught it using the slope-intercept method, but I think that the point-slope method has merit as well.
Practically speaking, we spend way more time in Algebra 1 focused on the slope-intercept form.
Because of that, I think kids are likely to remember that formula more easily than the point-slope form.
But, I will admit that the point-slope formula is often quicker in terms of number of steps, the solving is simpler (solving for b always throws off my kids), and the “answer” is already in the form that you need it.
With slope-intercept form, kids have to recognize what to do with the value they get for b.
Neither of these is particularly difficult, but deciding which way to teach it might be!😁
Google Forms Assessment
This assessment is a quick warm up, formative check, ticket out the door, homework check, or a mini quiz.
Here’s a <2 minute walkthrough of the assessment itself:
I love how the multiple choice grid appears in the student view. It allows you to assess perpendicular and parallel slopes in one problem and determines whether students realize those cannot be the same answer.
Students can use the slope-intercept method or the point-slope method (or something else!) to find the equations in this assessment.
I hope you’ve found some new resources for teaching parallel and perpendicular lines!
You’ve got this!
