123 – Reuleaux Polygons

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This topic was from a my favorite. Too much fun to not share.

122 – Thanks TI

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While calculating a routine integral from the BC exam, I got this warning (look at the bottom of the screen):

So useful. How questionable? Why not answer blue cow and then spit out “questionable accuracy”? Is this really an error that students want to see if they were taking an exam?

121 – Ambiguous Case

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Brought out the compasses and rulers and had the Precalc H kids construct some examples to investigate ASS (ha ha) and it’s ambiguous cases. We were using law of sines, so this investigation (hopefully) helped in making some of the ideas involved a bit more solid.


A fun part of the activity was the need for a 30 degree angle. With the first class I had them trisect a 90 degree angle (corner of their paper) by using the two fold trick, similar to folding a pamphlet. It ended up not working that well, their angles varied widely. So with the second class I had them create an equilateral triangle and bisect an angle. They were far more consistent and accurate with this method.

120 – Trig Mobile update

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What does the following data from Trig Mobile tell you?

Yep. My original measurement might have been off :-).

119 – Trigonometry Mobile

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You are interviewing at a toy manufacturer, you need to come up with a shape to balance the following mobile.



Student Work

(BTW, no guidance or motivation required. Just some simple rules and boundaries.)






Before they were able to actually try their shape out on the mobile, they had to analyze another groups shape. They had to write up a quick Quality Assurance document describing the performance of the other group, along with a prediction.

Sadly my original mobile setup was error prone, but the technique was improved with … more binder clips.




Subset of skills used/required:

  • Triangle area (using many different formulas)
  • Law of Sines
  • Law of Cosines
  • Area of circles (for those who decided to use a circle)
  • Area of hexagon (for the 1 group who made a hexagon)
  • Construction of a triangle given three sides
  • Construction of a perpendicular
  • Ambiguous case triangle



118 – Polar and Parametric in Desmos

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We’re working with Polar and Parametric Functions in BC Calculus. Desmos does a great job with each, but it’s nice to have a moving point to refer to so that the students can “see” the graph being drawn out.

Click either picture to go to the live Desmos page.

Here’s a polar example (by using the parametric version of polar equations!):

Screenshot 2014-03-27 at 12.28.15 PM

And here’s a parametric version:

Screenshot 2014-03-27 at 12.35.01 PM
Edit: Desmos responded with an improved approach!

117 – Post Quiz Feedback

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Here are some Pre Calc H kids getting immediate feedback and peer help for the feedback only (no grade) quizzes on Inverse Trigonometric Functions, and Transformation of Trig Graphs. Love this setup.


115 – Raspberry Pi

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No joke, a group had a blinking led (from python code) in less than 15 minutes after playing with the raspberry pi. Pretty damned cool.

Half the class is working in groups of 3 with a raspberry pi, playing around and seeing what they can do. The other half of the class is making a game in Greenfoot. We’ll switch groups after a week.