Wednesday, December 14, 2011

Candy Guess

I got the idea for this activity from two teachers, Mary Beth Runyun and Lynn Smith, who presented at the NCTM Regional Math Conference in St. Louis this fall. It is simple to do and takes little planning and gives a nice review of math vocabulary and number sense. I hung one of those big plastic candy canes full of candy that you can find at the store and put up the first clue..."Win this candy cane when you can guess this 3 digit number." I didn't make any big announcement about the activity- just waited to see if my algebra students would notice and ask questions on their own- and they did! I explained the only rule that I had for the contest was that they would only get one guess which they needed to write down on a piece of paper and turn in to me. Each day I added another clue getting more specific each day, i.e. Composite number, multiple of 5, an integer, etc. I knew they were hooked when I noticed two of my algebra students checking out the bulletin board for the next clues as soon as the bus dropped them off at school- before they were supposed to even be in the hallways in the morning! Several students had sheets with possible numbers that they would cross off each day after viewing the new clue. I have to admit I was pretty amazed. I was not sure that 8th grade students would care all that much about winning candy. Yesterday a student guessed the correct number, -645. They weren't expecting the number to be negative! Around 75% of my students had turned in a guess before the end of the contest. The best part of the activity was seeing them argue with each other about the possible solutions to the contest- using their math vocabulary.

1. Ok- I LOVE this idea and want to totally steal it. Would you mind posting all of your clues? I'm thinking I'd like to do this activity on a regular basis and it would be great to have yours to copy/adapt from. Thanks!!

2. Sorry- I have been busy with back to school stuff. Here is what I used for my Candy Guess activity. I forgot some of the clues...but these were the main ones for -645.
1- The number is a 3 digit number.
2- The number is a composite number.
3- The number is an integer.
4- The number is a multiple of 5.
5- Two of the digits are even numbers.
6- The number is divisible by three.
7- One of the digits is less than 5.
8- This number could be found on a number line. (See rule number 3.)
9- The hundreds digit has the largest value of the three digits.
10- One of the digits is a multiple of 3 and is greater than 5.
11- The tens digit is not odd.
12- The average temperature of Neptune in degrees Fahrenheit is a bit warmer than this 3 digit number! (This clue finally gave it away that the number was negative. One Student had 645 after the 4th day but was out of the running for having a wrong answer. I did give him a runner up prize!)

The first student with a correct answer won the contest however, I only allowed one guess per student. Once they had made a guess they were out of the running for the prize if they made an incorrect guess. I am definitely doing this again...maybe even trying something using polynomials and exponents.

3. Awesome! Thanks for sharing, Amy