Radiation Sanity Chart

With news reports of radiation from Japan being found from California to Massachusetts — and now even in milk — math teachers need to help our students put it all in perspective.

xkcd to the rescue!

Pajamas Media offers a brief history of radiation, plus an analysis of our exposure in Banana Equivalent Doses:

And the EPA offers a FAQ:

[T]he levels being seen now are 25 times below the level that would be of concern even for infants, pregnant women or breastfeeding women, who are the most sensitive to radiation… At this time, there is no need to take extra precautions… Iodine-131 disappears relatively quickly in the environment.

— Centers for Disease Control and Prevention (CDC)
pages 4-5 of EPA FAQ

[Hat tip: Why Homeschool.]

Can You Find These AWOL Math Websites?

by √oхέƒx™ via flickr

In the course of my bloggy spring cleaning, I’ve made some terrible discoveries. Some of my favorite resources have disappeared off the internet. Or perhaps they’ve moved, and I just haven’t found their new homes.

Do you know where these websites went?

A Very Short History of Mathematics

This irreverant romp through the history of mathematics by W. W. O. Schlesinger and A. R. Curtis was read to the Adams Society (St. John’s College Mathematical Society) at their 25th anniversary dinner, Michaelmas Term, 1948.

Internet Archive’s Wayback Machine found a copy, but I’d love to replace this link with the article’s new location:

[Warning: Do not attempt to read this article while drinking coffee or other spittable beverage!]

Update: James Clare found the article’s new home here. Thank you!

Continue reading Can You Find These AWOL Math Websites?

Bloggy Spring Cleaning Continues

Still on course with my state-sponsored blog overhaul, and Google Reader insists on displaying every old post as new. What a nuisance! The email feed seems unaffected. (And not everyone is having the problem with Reader, either — see Comments below.)

Amazon won the reader poll (and it’s my favorite, too), so I’m converting all my old affiliate book links to just-plain Amazon links. At the same time, I’m checking for dead links and other dust bunnies among the old posts. I’ve worked my way up to June 2007 — four more years to go — and then I’ll start on my blogroll (a monster task!) and other pages.

Like normal housecleaning, it never ends …

Does Anyone Know Where the La Habra Math Timeline Went?

The worst news so far is that the La Habra Math History Timeline has disappeared. What a shame! Does anyone out there know where it might have gone? I would love to link to its new site.

Thanks to the Wayback Machine, here’s a glimpse at the old site. Math discoveries, publications, and other tidbits — from paleolithic number bones to the present:

I changed the links on my Math Resources page to the wayback pages, too. My apologies to those who got sent to a junk site by the old, defunct links.

Math Teachers at Play #36 via Math Hombre

The carnival is posted!

36 has long been one of my favorite numbers, but faced with this carnival, it was hard to figure out why. It’s a square number that’s a product of two squares, but that’s not too rare. (Why?) It’s the 6th perfect square and the sum of the first six odds, but that’s not too remarkable. (Why?) It’s the 8th triangular number, but not a Sierpinski step or anything… wait! It’s a square triangular number? How common is that? 1, 36, then…?

Read the whole thing…

What Is the Name of This Book? … Is Back!

In the process of updating old book links (and otherwise cleaning up old posts), I’ve been spending more time than normal at the bookstore. I just noticed that Raymond Smullyan’s What Is the Name of This Book? is scheduled to come out this August — and it’s already available for pre-order. WooHoo!

Can To Mock a Mockingbird be far behind? Oh, and Alice in Puzzleland — I want that one, too!

Poll: Where Do You Buy Books?

Thanks to our insolvent state government, I need to go back and change all my book links. I never made much from the Amazon affiliate program, but it usually managed to cover Kitten’s school books. Oh, well, at least they haven’t closed the public libraries … yet …

Since I’m changing the old links anyway, I thought I’d give you all a chance to voice your opinions. Shall I continue to reference Amazon.com, or would you rather my book links took you to Barnes & Noble?

P.S.: For my rss subscribers, I apologize for the flood of old posts. Every time I make a change, it seems the feed releases the post anew. I’m afraid this will continue for a few weeks, since I’m using the affiliate mess as an excuse to do other long-neglected blog clean-up tasks as well. With 596 published posts, that will take awhile. I hate housecleaning!

Game: Times Tac Toe

Photo by jma.work via flickr.

I’ve been working on a book of math games for homeschoolers and other teachers. I hope to get it published later this year, but the editing drags on. Would anybody like to draw the illustrations?

Meanwhile, here’s a 2-player game your students may enjoy…

Set Up

Print out a blank times table chart and place it between the players. Each player will need a colored marker, and the colors must be different enough to be easily distinguished.

Remove the jokers and kings from a deck of poker-style playing cards, but leave the jacks (= 11) and queens (= 12). Shuffle the deck, and place the stack face down as a draw pile.

Continue reading Game: Times Tac Toe

Quotable: Math vs. Writing

Seen at kitchen table math, the sequel:

I can recall the deep satisfaction I felt on the all-too-rare occasions at school when the concepts or formulas fell into place. It seemed an entirely different discipline from writing, where something arises from a blank page through a combination of hard work and patience, with a sliver of creativity.

With math, the experience is more like discovering something that’s always existed and finally decided to stop playing hard-to-get.

Ralph Gardner
Making Math Fun (Seriously)

Continue reading Quotable: Math vs. Writing

Still Relevant After All These Years

We have an interesting discussion going in the comments on The Problem with Manipulatives. I mentioned a vague memory of a quotation. Now I’ve found the source.

Originally published in 1970:

The continuing hullabaloo about the “new math” has given many a parent a false impression. What was formerly a dull way of teaching mathematics by rote, so goes the myth, has suddenly been replaced by a marvelous new technique that is achieving miraculous results throughout the nation’s public schools.

I wish it were true — even if only to the extent implied by entertainer (and math teacher) Tom Lehrer in his delightfully whimsical recording on “The New Math”:
“In the new approach, as you know, the important thing is to understand what you’re doing, rather than to get the right answer.”

… Indeed, there is something to be said for the old math when taught by a poorly trained teacher. He can, at least, get across the fundamental rules of calculation without too much confusion. The same teacher trying to teach new math is apt to get across nothing at all…

Martin Gardner
Foreword to Harold Jacobs’ Mathematics: A Human Endeavor

Unfortunately, I can’t embed the Tom Lehrer song Gardner mentioned, due to copyright restrictions, but here’s a link to YouTube: