How I Teach Trig

Trig is one of my favorite units to teach in Geometry. I feel this is one of the few units most of my students feel REALLY confident about.

There is ONE thing I do consistently from year to year that I feel has made a huge difference in student understanding. 

A WORD WALL

I know what you are thinking. This isn't just any ordinary word wall. This is an interactive word wall that focuses on the names of the sides of the triangle. 

Why did this work so well? I laminated each piece and put magnets on the back. This allows me to rotate the triangle and change where theta is in the triangle. More about this when I talk about Day 1 below.

How do I structure my unit?

I teach on an 85 minute block schedule.

Day 1

We just talk about vocabulary and the 3 trig ratios. We start by using THIS (free) magnetic word wall, going over a variety of situations. 

"If the triangle looks like ____ and theta is ____, where is the hypotenuse? Where is the opposite? Where is the adjacent?"

We would go over 10 or so examples. Students are then given THIS set of task cards to sort, classifying between the three different sides of the triangle.

Then we would talk about the three trig ratios, and JUST practice setting them up. We don't do anything with a calculator or solving the first day. Their homework has them practice setting up the trig ratios.

Day 2

Before teaching kids how to determine which trig ratio to use, I have them do THIS sine, cosine, tangent task card sort. I tell them to do the best they can as a team to determine which trig ratio they think they would use to solve for x. I give them 5-10 minutes to work on this (depending on how fast they are).

I put a picture of #5 on the board and ask teams how they decided which trig ratio to use. I don't give them the answer, instead waiting for teams to explain their thinking. I may have to ask questions to help them get to the correct explanation.

After seeing why #5 went under Sin, we looked at how to solve it together. 

I repeat the same process with #15. I do this one next because it is also Sin, but they are now solving for the hypotenuse rather than the opposite, so it brings up great questions about the setting up and solving right away.  (I always have my kids turn their equations into proportions by putting sin, cos, or tan over 1 and then cross multiply.)

We repeat the process with #2 and 3 as a class.

I then have the kids do a handful together as a team, skipping the ones that require the inverse trig functions. By this time, students are starting to get the hang of setting up and solving the trig ratios. 

Their homework this night is THIS trig mystery. I like mystery activities because they are self-checking, giving kids that immediate feedback that is so important.

Day 3

We spend day 3 practicing, practicing, practicing. The kids start off doing a few examples with their team just as a refresher. They then work on THIS digital self-checking activity (they skip the inverse questions). I love self-checking activities because it eliminates the "Is it right?" questions and turns them into, "I got this wrong and can't figure out why. Can you help?" This then allows me to spend more time with remediation rather than checking.

Day 4

We start class with a short 4 question quiz. When students are finished, we move into talking about Inverse Trig. I start the lesson by putting up one of the task cards from Day 2 where the angle is missing and ask them how it is different. After they realize they are being asked to find the angle, we transition into talking about Inverse Trig. We do a few examples together, then students work on problems with their team. 

Their homework this night is THIS Inverse Trig Maze. Mazes are another great way for students to feel confident in their answers as it is a self-checking activity.

Day 5

Today is the day we put everything together. Students work on THIS Trig and Inverse Trig Color by Number activity. This is a great activity because it is self-checking and students are able to gain confidence that they have the correct answer. They also love coloring! When they are done, I have them cut out their pictures and hang them up. 

Day 6 

Now that students have confidence solving trig problems, I introduce Trig Application problems. We do a few story problems together. I focus on drawing and setting up the problem together. I have the students solve the actual problem with their team. 

I then give them THIS Trig Application Tic-Tac-Toe activity. This is a great activity because it allows students some choice in which problems they solve. This resource also makes differentiation easy because there are 3 versions with a different number of required problems on each. 

Day 7 

It's project day! I love ending my units with a project requiring students to put everything from the unit together. 

My students must write their own trig application problem. It can be a problem looking for a side or angle. Students are to write their problem on a poster as well as include an illustration. I then have the students make an answer key on a separate piece of paper and tape it to the back.

Day 8

I post a few of the trig application posters and have students go around solving some of the problems. They can then check their answers by looking at the answer key on the back of the poster. I give them about 20 minutes to work through a few posters. We then work on the Unit study guide.

Day 9

Test day!

I have found this pacing to work well for my students on an 85 minute block schedule day. If I had 50 minute classes, I would add a few more days of practice for each topic. I also don't include special right triangles in my unit. This is the last unit we teach in our first semester, so I start second semester reviewing trig and then teaching special right triangles through warm ups.

I also have a YouTube video all about teaching Trig. Watch the video HERE!

I hope this has helped you get an idea of how to teach Trig in your math classroom!

Have a mathy day!