Card Auction (Introducing dependence)

Last month, Nat Banting described a fantastic task on his website called the Dice Auction. You should really just read the original post, but I will summarize it as best as I can here.

Cfh3p4sUsAEk2Wj.jpg_largeThe premise is that you are invited to an auction, and given a budget of $10 [I changed the budget to $15 for my students to encourage a bit more risk taking]. Everyone at the auction has the same budget. The participants are all bidding on certain events that may occur when two 6-sided dice are rolled (e.g., both numbers are greater or equal to 5; a single 2 is rolled; both numbers are odd; etc.). After all the events have been auctioned off to the highest bidders, the two dice are rolled 20 times. Each time the event that you purchased occurs, you collect a prize. Bidding always begins at $1 and goes up in increments of $1. You cannot bid against yourself. The order of the events up for auction is known beforehand. If you choose not to spend (some, or all of) your money, the auctioneer will sell you prizes at a cost of $2 per prize after the bidding has ended. Your task is to get as many prizes as possible.
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On McNugget math (and being less helpful)

Another great Pi Club (still a working title) meeting.

Today, we worked on the McNugget problem (a case of the Frobenius/coin problem), which goes something like this:

Chicken McNuggets come in packages of 6, 9, and 20. Assuming money is not a factor and that you can only buy full packages, what is the largest number of Chicken McNuggets that you cannot buy?

mcnuggets

(Of course, I brought McNuggets for the occasion. You know, as manipulatives…)

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When you ask the kids to come up with the club name…

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AARDVARK: Amazingly Advanced Recreational Division Verity Academic Researching Kids

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BUFF KANGAROOS: Beautifully Understanding, Fully Functioning Klub of Academic Nerds Giving All Races Opportunities of Schooling (interesting social justice twist here)

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BODY BUILDER: Batch Of Dubious Young Budding Unparalleled Intellectuals Like Daunting…

 

Personally, I’m rooting for BODY BUILDER.

Pi Club: Round 2

First things first, Pi Club has a new member – and SHE is a wonderful addition to the group! WOOP WOOP, girl power!

Today, we worked on two problems. First, the lightbulb problem (found here):

There are 100 light bulbs lined up in a row in a long room. Each bulb has its own switch and is currently switched off. The room has an entry door and an exit door. There are 100 people lined up outside the entry door. Each bulb is numbered consecutively from 1 to 100. So is each person.

Person No. 1 enters the room, switches on every bulb, and exits. Person No. 2 enters and flips the switch on every second bulb (turning off bulbs 2, 4, 6…). Person No. 3 enters and flips the switch on every third bulb (changing the state on bulbs 3, 6, 9…). This continues until all 100 people have passed through the room.

What is the final state of bulb No. 64? And how many of the light bulbs are illuminated after the 100th person has passed through the room?

They didn’t take too long to work this one out. Great conversations were had.

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I think I started a math club

It began with one student. I noticed pretty early in the semester that grade 9 math was old hat for him and that he needed a challenge, so we started to meet once a week or so to talk math and work on some interesting problems. (During our first meeting, we proved that the square root of 2 is irrational.)

Then, he brought a friend. Who eventually brought two more friends. (If you’ve been doing the math, you might expect 8 students at our next meeting; alas, there were only 5. But wait, that’s five students who want to do math outside of math class!) We did a few problems, but mostly spent time discussing the idea of doing independent projects that the students would present to the class on the last day before Christmas break.

Today was the first session that really felt math club-y: I ordered some pizza, gave the students the Crossing the Bridge problem (thanks, Sadie!) and some white boards, then set them loose.

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