# Polygon Pile Up

When it comes to angles involving parallel lines, triangles, and other polygons I’ve always assumed my grade 9 applied students “get this”. I’ve felt that angles were an easy topic. I guess I thought this because most students seem pretty happy when solving angle problems and for the most part being doing pretty well on assessments. However, this year I noticed two inadequacies that I am trying to address.

1. Most of my students didn’t actually know what an angle measurement of 65 degrees really means.
2. They have a hard time determining what information is needed when solving multi-step angle problems. Lack of a good strategy.

When having students determine angles in triangles almost all of them knew that all three angles should add to 180 degrees. The trouble came when I saw some answers like this (from more than one student).

What bothered me was the location of the 40. I wondered why outside the triangle? I pressed this student for more info. I asked him to draw me any right triangle and label the three angles.

Hmmm…I asked him to point to one of the angles. He pointed to where he labeled the 85. What I found is that this student was mixing up length measurements with rotational measurements and he was not alone.

I found a great activity to hit this head on. Laser Challenge from Desmos worked wonders to get my students to understand and experience rotational measurements. Students have to enter values to rotate the laser and mirror to hit targets.

My students “felt” what 60 degrees is. Experiencing that rotation made all the difference to clear up what we were actually measuring. When second semester rolled around and my new crop of kids came in we started with this activity right away.

Most of our students struggle with solving complex problems where they have to think of a strategy. Before I gave them something like this,

I wanted to them to experience what information would be useful to know first. I decided to turn the problem around and inside out.

I gave them this.

I wanted them to think backwards….just like we need to do sometimes when solving longer problems. On the “easy” side most filled in 3 angles in the quadrilateral. What was great was that prepared them to think what we could leave out for the harder one. This simpler diagram challenged my class to think, plan, and strategize!

It was great to do this before we introduced this puzzle Jim Roesch, Kristyn Wilson, and myself created:

[There is a video embedded here — Can’t see it? Click through to the post page]

Here is the puzzle

Click to download a PDF copy to print.

And to really challenge yourself or your students here is a blank one. Can you fill it in so it’s “hard” to determine that indicated angle? What is the least amount of info you can give to bring out the most amount of thinking? Share them out!

# Peregrine Falcon – Fastest Animal Alive

I need your help…..

I modified this video originally from Vox for a colleague and her math class.

Could you watch this short video on peregrine falcons with your students….

and then Complete these tasks?

1. What do you notice? What do you wonder?
2. What questions will you work on with your students? Work on them.
3. You can watch the full video here to see/hear un-bleeped values.
4. Take pictures of any thinking your students show you. Send me comments & pictures on Twitter, email, or here.

I’ll update the post with your student’s work.

Thanks,.

# Appointment Clock

In class today we practiced, error-checked, discussed solutions, got peer feedback, got teacher feedback, smiled, laughed, and cringed. Today’s class was supposed to be boring. We were supposed to just practice solving polynomial and rational inequalities. Boring right?

A few years ago I saw an activity structure called Appointment Clock from an English teacher in my district. It was one of those structures you see at a PD day and think… “that’s kinda cool” and then the weekend happens, and by Monday it’s gone. For some reason, this weekend, years later….it popped back into by brain.

To start all students got an appointment clock handout.

They were given two to three minutes to circulate around the room and schedule “an appointment” at the indicated times.

Next, they were given ONE inequality (list of inequalities) and about 7 or eight minutes to solve it. They were to write the solution to their inequality on the handout and keep it hidden from the other students. They were to check their solution using Desmos. I circulated to help anyone who needed it. “Now, this inequality is YOUR inequality….you are the master of this one.” Once everyone was ready, I announced, “Get up, and move to meet with your 2 o’clock appointment. Show your new partner your inequality. Complete their problem in your notes and check with them to verify your answer.” I gave them 7 minutes. This is where great stuff happens. They check with each other to find mistakes, get feedback, improve. After the 7 minutes or so, I announced, “Now, meet with your 10 o’clock appointment and repeat the procedure.” The structure is very much like Speed Dating

We did this for the entire class. Every minute was worth it!

At no time was practicing solving polynomial and rational inequalities boring. Not today!

# Really Big Lights – A math problem

Here’s a really big problem you can work on with your students this holiday season.

Act 1:
Show them this video and ask: What do you notice? What do you wonder?

After allowing them to voice their noticing and wonderings guide them to wonder: How big is that new light? How many times bigger is the big light compared to the old light? How many Really Big Lights would you have to put up to cover the same length as last year?

Act 2: Here are some images to help make some conclusions:

Guess: How long is the big light? How many times longer is the big light than the small light?

Reveal:

Guess: How many small lights are in one string that stretches 15 feet?

Reveal:

Work together to determine how many Really Big Lights would replace the string of 50 lights? What assumptions will you make?

Act 3: Reveal

Why might your calculated answer be different from the answer shown?

If you had 50 Really Big lights how long would could they reach? How many cars could you put in that garage?

Grab all files for this activity

You can see more info about the lights over at http://reallybiglights.com/