Monday, November 25, 2013

A Great Problem for Mathspot.Net

I found this problem on, a great blog by Lisa Englard and really liked it.  It was co-written by Lisa and first appeared in Teaching Children Mathematics, Math by the Month column, October 2013.  It is here with Lisa's permission.  

Jared’s mom works for a company that publishes books. When he visits her office, he likes to watch the machine that binds the books. Mr. Green, who runs the machine, told Jared that the machine can bind 12,000 books in 1 hour and 20 minutes and that the machine runs steadily for 10 hours every day. He also found out from Mr. Lee in marketing that last month, the company printed fiction and non-fiction books in the ratio of 4:1, with 540,000 more fiction books printed than non-fiction. Jared’s mom asked him if he could use all the information he learned to figure out how many days it took last month to bind all the fiction and non-fiction books that were printed. Does he have enough information? If so, how many days did it take? If not, what other information does he need? 

Tuesday, November 12, 2013

There's a Sale! What Percent are you Saving?

I was sitting at the airport, one of my favorite places to find math problems. I'm also an accomplished eavesdropped.  An commercial played on TV, touting a huge savings of $10 off every $25 spent.  The woman behind me turned to her friend and asked, "What percent savings is that?"  I thought it would make an interesting question to ask our students, since they might have lots of different ways to show their number sense as they solve it.