## Monday, March 7, 2016

### A Huge Bunch of Lovely Links

I have so many tabs with cool math posts, I don't know if I can possibly get them all into this collection. (I never seem to have enough time to finish, and then more goodies accumulate.)

Math & Teaching Ideas I might use

Problem Solving

Using Desmos
• An introduction to desmos
• Linearization in Calculus, an amazingly detailed lesson using desmos, with commentary about how students did with it
• I do a unit in trig called Days Of Our Lives, using minutes of daylight on each day of the year as data, and getting students to construct an equation for it. This Moon Illumination project someone made on desmos using the activity builder looks like something I could imitate. (Where did they get their data? Who made this?)
• Desmos art project

On Teaching

Science

Statistics

Estimation & Elementary

Math for Parents

Social Justice

Playing with Math
• As usual,  this game (called this game is about squares) is more about logic than about math. What I'm finding interesting is how impossible it seems, and then when I (and others) go away and come back, it can suddenly seem so easy.
•  Tracy Zager wrote a great post on evaluating math fact apps. Lots of good ones are mentioned in the comments. [My comment: I would really love to be able to find this app online so I can recommend it. I have this game on my phone. It seems to be called 1 Whole. There are rectangular shapes that fill with liquid. You push one toward another and they go together if the sum is less than or equal to one. You watch the liquid rise. If it’s 1, it goes away and you get points. You keep going until the screen is full of things that won’t combine (sum > 1). There is no time pressure, the conceptual basis seems strong to me, and mistakes aren’t allowed. No penalties, no bad sounds, it just won’t work. I think it’s pretty good. I wish I could find it online. Cna anyone help me?]
• Kids like doing the simple math involved in thinking about the Collatz Conjecture. [Start with any number (whole,  >1). If odd, triple it and add 1. If even, cut in half. Repeat. Does this always end up at 1? Conjecture is 'yes'.] Mathematicians don't know the answer, but they like to explore the question in sophisticated ways. Here's a post on what sorts of functions come close to modeling the number of steps it takes to get to 1 from each number.
• This game would have made it into my book, I think. Cross Over looks like it has enough strategy to entertain us jaded adults, and it's for addition and subtraction practice. Coolo.
• Not math. Go. Learning to play go
• New game for iphone (really, it's logic not math), Ringiana
• I love surreal numbers. I need to come back and read this more carefully when I have more time to play with it.
• A silly little game. Totally violates Tracy's criteria (nothing timed). But mathy folk may like it. How many primes can you identify in a minute (with no mistakes)?  (Use y and n for y and no.)

Books
• Here's a great list of fun math books, compiled with a 14-year-old in mind, but almost all good for adult mathophiles too. I think this list came from the same question and has a different set of books.
• My publisher is having a sale. All 5 books published by Natural Math for \$50 total. What a great way to expand your playful math collection.

1. Great linkfest! Isn't it amazing how much wonderful math there is for free on the web?

The sailboat video is almost begging for a 3 act (a la Dan Meyer):
(1) act 1: opening still of the boat, already leaning a bit, bridge in the background.
What do they notice, what do they wonder? What info and data do they need?
(2) act 2: diagram showing height of bridge, length of mast (maybe also info on width of opening, depth of water, length of keel?)
(3) act 3: conclusion of video
(4) extensions: what about the keel? what is the largest boat that could get through? Boating wonderings: relationship between keel length and mast height? how heavy were the weighted bags? how did they achieve that leaning angle, how did they manage the angle of lean, and how did they bring the boat back upright?

2. wow - what a list! Thank you for including some of our posts.

Thought you might like to see a couple of the projects you mention with kids:

The double Mobius heart one I did with a bunch of kids from the neighborhood - it was fun to see their reactions:

https://mikesmathpage.wordpress.com/2015/05/31/cutting-a-double-mobius-strip/

The strange harmonic series fact blew me away too - we played around with it and explored why it might be true:

https://mikesmathpage.wordpress.com/2015/06/30/counting-and-a-fun-harmonic-series-fact/

Also, I think there is a typo in one of the links - the link in "Sam Shah made this fabulous website" isn't working for me

3. Link fixed. Thanks for pointing it out!