Welcome to my math blog! The purpose of this blog is to help you stay informed about our learning and experiences that have taken place during our math class. I have also included links your child (and you) may want to use in order to supplement math learning in 5th grade.

Monday, April 27, 2015

Would You Rather: Pennies vs Quarters

Today we problem solved.  I posed the problem:

Would You Rather...

I explained that I had read about a man who had driven to his bank with 500 pounds of pennies in the back of his truck.  He had been saving pennies for years and was finally making a deposit.

I told them that I had found this WYR and I thought of the man and his deposit.  I had my students open the Google Doc:  Would You Rather - Pennies vs. Quarters and I asked them to predict whether they would rather have the pennies or the quarters.  I also asked them to explain why.

Next, I asked them to tell me what they KNEW about the problem.  They explained that they knew we had 500 pounds of pennies and that each penny's value was \$.01.  I asked them what they NEEDED to know.  They wondered how many pennies were in a pound.  We visited a site that explained, exactly that:

We determined that we would use the number of zinc pennies in a pound.  I asked them how we would use the facts that we now had to determine the value of 500 pounds of pennies.  I asked the students to create an expression to help us solve the problem.  Before beginning, I asked the class to remind me of the difference between an expression and an equation.  It took some prompting, but finally, someone in each class remembered that an equation includes an equal sign, while an expression does not.  Using our expression (500 x 182 x .01) the number of pounds times the number of pennies in a pound (91,000) x the value of a penny (.01) gave us the answer \$910 for 500 pounds of pennies.

Next, we followed the same process for the quarters.  We KNEW we had 40 pounds of quarters and that each quarter was worth \$.25.  What we NEEDED to know was the number of quarters in a pound.

This time our equation (40 x 80 x .25) gave us a value of \$800 for 40 pounds of quarters.

Finally, I asked the students to write a conclusion statement to either defend or refute their prediction:

After finishing up the assignment, students "turned in" their work through Google Classroom.  Then we posted their work to Kidblog.