mathcoachblog

A famous face met students as they enetered today:

Our friend Gauss…someone on my math Mount Rushmore.  It makes me sad that our country puts politicians on money, while others have used the opportunity to recognize real contributions…end of rant.

Today I offered a challenge whose tone has changed in the face of technology:

Find the sum of the first 10,000 positive integers.

In the past, I have used 1,000 as the ceiling, and observed as students mostly used a “brute force” method to find a sum. Offering candy to the first person to provide a sum, I settled in, knowing this task often takes some time and discussion.

Then….an “I got it” from the back of the room, and a correct answer from a student who Googled the answer.  Sigh…..  Damn you technology and good wifi!  I guess I haven’t given this problem since before I served as a district instructional coach – 3 years makes a big difference here.

In my afternoon class I altered course, providing a clear “no Googling” message with the problem. But I was once again (almost) sabotaged as students used my technology openness against me. Yesterday, we had learned about summation notation, and had a brief tutorial on how to enter summations on graphing calculators. This led to some attempts to simply enter the sum…but with some semi-disastrous results:

So close, but yet so far. And while I’ll save my story of Gauss and his amazing sums for tomorrow, we had a fun debate on notation and communication.

David Letterman has his Stupid Pet (and human) Tricks…so today in class we started Stupid Student Tricks (please read that carefully —- stupid is describing the trick).  My classes understand I will begin each day a short opener, and I have now given them the opportunity to participate in the process.  On Edmodo, they can submit an idea for a class opener – it can be a video, a challenge, a picture, a story – to share with the class. Every Wednesday, one idea will be chosen to be the class opener. Chosen ideas will receive a bonus quiz grade during the semester. I’m looking forward to the ideas the kids choose to share!

RYAN’S CUBES

My first student “opener” volunteer is Ryan, who shared his skill of identifying perfect cubes.  Calling volunteers to the board, he asked them to think of a number from 1 to 100, and share it with the class (but not him).  Then, the volunteer cubed the number and the product was written on the board.  Within seconds, Ryan gave the original number.  It’s a pretty good trick, and one he has become quite quick with.  To show how the “trick” is done, Ryan shared a video from Scam School, a neat series of everyday tricks and scams.  Enjoy it here:

After last week’s experience with Sierpinski’s Triangle, I was eager to see other math landmarks my students had encountered. Knowing that our next unit will be on sequences and series, it seemed like a perfect time to share this:

“Von Koch curve” by António Miguel de Campos – self made based in own JAVA animation. Licensed under Public domain via Wikimedia Commons.

Many students identified “the Snowflake” immediately, and I filled in the “Koch Snowflake” gap.  Soon, our room was filled with ideas of fractals and self-similarity. We grabbed markers, and started drawing on our desks.

How many sides does this have?

What is its perimeter?

Tomorrow, we will look at patterns and develop explicit formulas for them. Today’s opener planted some seeds I hope to sow during tomorrow’s discussion.