My school doesn’t cover interval notation in its curriculum. We focus primarily on inequality notation, although I tend to use the more specific set-builder notation. Each representation has its merits, so I wanted to include interval notation more this year, as an occasional aside. I’ve made a poster (8.5×14) that I’m going to hang up in my room to help students see the connections between the inequality symbols, the choice of open/closed points on a number-line, and the choice of soft/hard brackets in the interval notation. I’ve also made a color-coded version where students can ask themselves, “Can I include this point?” Green=”yes, include”, and red=”no, exclude.” Half of my classes this year are geared toward students who had received <40% in their last math class, so I’m hoping that the stop-light colors can make this yes/no, include/exclude concept easier to grasp. [NOTE: Thanks to lovely conversations on Twitter, it’s been noted that the green/red combination could potentially be dangerous if you have any colorblind students! I’m working on another, more color-friendly version that you can use, as well. I will update this post when it’s been made!]
Before I hang the laminated poster up (I add posters throughout the year as topics arise), I’m going to print another one and cut up the grid into the 36 individual rectangles and hand one piece to each student in my class (if there are fewer students, ask your class “who wants another piece?”–I always seem to have a bunch of volunteers because this means they’ll get to talk to more people!). Students will then find the two other classmates who have representations equivalent to their own card. Once a triple has been found, students will check their cards with the teacher. If they are correct, they will move around the class helping the remaining students. If they are incorrect, they will review which card(s) in their triple didn’t belong as a group of three, and then go back to finding the equivalent representations.
Would you like a copy of the reference poster? Get the color and the black and white versions here! (It’s free!)
A while back I made a display for special right triangles, and realized I never shared the files! You can download the PDF and the editable Publisher files here! You’ll need to download the free font HVD Comic Serif Pro if you choose to edit the Publisher file yourself.
Here’s a picture of the pre-laminated pieces. I took a few pieces of the finished product on my walls in the classroom, but each one had a nasty glare from the laminated finish.
Throughout the year, I will be adding more justifications as they come along. The next batch that we will come across will be about segments. From there, we’ll talk about angles, congruence, similarity, and more!
Here’s what I’ve got so far! What justifications you most want to include in an edited list? I plan on using these primarily for two-column proofs in geometry.
PDFs: Justify It! Posters (Color) and Justify It! Posters (Black)
The last few weeks of this summer have been filled with poster-making to spruce up my classroom and to make the walls more of a resource to my students. To determine what would be the most useful posters to make, I’ve been doing a lot of reflection about last year. One topic that I wish I had a public record/anchor chart style poster for was reference angles, which is covered in our Trigonometry unit in Algebra 2. I’ve been contemplating a lot about how I’d want it to look and had considered making an entire unit circle poster, but decided against it since I felt as if that promoted students to memorize all of the values.
I really want to get my students to the idea that they can derive as much or as little of the values as they desire. If they want, they can derive them all from scratch, and we discuss how to do this in class. We then talk about how if they feel more comfortable with memorizing them all so they can work quicker on a test/quiz, then they are free to do so as well. We then have the conversation about my own personal preferences: I memorize the sine and cosine values for the first quadrant. From there we can easily get tangent by dividing the sine value by the cosine value, and we can think about the properties on the coordinate plane to get the appropriate signs for any other angles. Most students choose to take my approach as well since it is a nice middle ground.
Here’s the PDF File – Reference Angles Poster. I sent mine over to my school’s print shop to be printed on 24″x36″ paper. You can print it on standard 8.5×11 paper if you select “Fit” or “Shrink Oversized Pages” on your prniter’s menu.
My last project for the summer will be making labels for 0, 90, 180, and 270 degrees with their corresponding sine and cosine values to be put around the wall clock in my classroom.
Happy Sunday! This marks 3 more weeks until I go back to school. How much time do you have?