Todd Feitelson 🏒

9-12 Math Teacher. Algebra 2, AP Calculus, Geometry. Wolfram Innovator Award 2019. Fun Fact: My Dad was Martin Gardner’s accountant. He/Him #MTBoS

[Todd Feitelson 🏒 @toddf9]

@RochelleTelfer Pirate game day 2024!

[Todd Feitelson 🏒 @toddf9]

Tomorrow: last class of the day, year and high school for my AP Calc students. Got a favorite game/activity to suggest? #mtbos

[Todd Feitelson 🏒 @toddf9]

@RochelleTelfer More joy. Pirate game day!

[Todd Feitelson 🏒 @toddf9]

@Desmos 3D is live! I've been waiting for this!

I took a student project from Algebra 2 that is from another platform and imported it to desmos. It's done using systems of inequalities. Very accessible!
#Desmos3D

https://t.co/6d96RiOB8m

[Todd Feitelson 🏒 @toddf9]

Another close one

[Todd Feitelson 🏒 @toddf9]

My AirPlay code was oh-so-close to the “I’ll buy you all pizza” number.

[Todd Feitelson 🏒 @toddf9]

I could spend a full week in class on this cartoon. #NoticeWonder https://t.co/8CyKxTJytm

[Todd Feitelson 🏒 @toddf9]

@mrdardy @KarenCampe That’s where I stopped reading for about a year. But my daughter encouraged me to finish it so I did and I’m glad I did.

[Todd Feitelson 🏒 @toddf9]

@mrdardy @KarenCampe Yeah, it was the same with me I think, but I coach, love and play hockey. That made me uncomfortable too. In the end, though, I felt like the book shared my sensibilities. I’d be curious what you think if you make it through the book.

[Todd Feitelson 🏒 @toddf9]

@mrdardy @KarenCampe I actually stopped reading it at some point, maybe where you are. It was kind of upsetting and seemed like it might move in a cliché direction. But - I came back to it, and I actually found it dealt with some difficult issues pretty well. The sequel is on my list for this summer

[Todd Feitelson 🏒 @toddf9]

@bowmanimal Reminds me of this old Car Talk episode.

https://t.co/TXniClcDho

[Todd Feitelson 🏒 @toddf9]

Every auto-biography should end
“….and then I sat down to write this.”

[Todd Feitelson 🏒 @toddf9]

My AirPlay code was oh-so-close to the “I’ll buy you all pizza” number.

[Todd Feitelson 🏒 @toddf9]

@suffolkmaths Fine question. Here’s a summary in a tweet. Glad to add more if needed.

[Todd Feitelson 🏒 @toddf9]

@shirky17 @mathhombre Yes. Recorded video. Projected and marked ball at three spots. Projected @desmos grid on board. Used coordinates to find a,b and c (solved system using matrices). Plotted and traced equation. Replayed video. Voila! #LessonInATweet

[Todd Feitelson 🏒 @toddf9]

Quadratic ball toss day again! “So satisfying.”

[Todd Feitelson 🏒 @toddf9]

“When the math is over”

[Todd Feitelson 🏒 @toddf9]

@DavidKButlerUoA @jamestanton Intermediate Value theorem! Related to one of my favorites: at any given moment there are two antipodal points on the globe with the same temperature.

[Todd Feitelson 🏒 @toddf9]

@joshuazucker @KarenCampe @mrdardy I agree - it's different than "the set of all points where the function is increasing" (which is not something we typically ask about.)

I really, really like the subtlety in these definitions - I think they're kind of beautiful. And yet, very unimportant at HS level at least.

[Todd Feitelson 🏒 @toddf9]

For teachers, today is the Sundayest of all the Sundays.

[Todd Feitelson 🏒 @toddf9]

@mrdardy IMO, it's highly pedantic, pretty unnecessary to beat kids up with, but it does speak to the importance of detail in definitions. I believe the AP in these cases is even accepting of either the open or closed interval as a correct solution.

[Todd Feitelson 🏒 @toddf9]

@mrdardy I think of it as "cutting some slack" to those endpoints -- we don't really care about the behavior outside the interval. In this case, the question asks "state the intervals where cont." instead of "state all values where cont." I think that's the difference.