Lesson 14

Break Even Day 2 of 2

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SWBAT set up and solve equations with two equivalent expressions.

Big Idea

Use cups of pennies to learn about setting expressions equivalent to find that magical "Break Even" point.

Bellringer: Scheduling Big Rocks

5 minutes

Previous Preparation

Preparation for this lesson shouldn’t take very long.  Make copies of the paper balance scale and laminate them if you have time just to preserve them for later use.  I would not recommend trying to get really creative and bringing in real balance scales from the science classroom, if your school has those.  Pennies have been made of two different materials through the years (copper and zinc) and each have a different weight but same appearance.  The date on the penny determines the material used to create the inside of the coin.  I have a lab just for this in the systems of equations unit, so wait until then to actually weigh these coins. 


I went to the bank and cashed a ten-dollar bill for rolls of pennies.  I put a roll of pennies into a paper-drinking cup and gave each group a cup of pennies and a paper scale.

Closing the Lesson

15 minutes

We closed the lesson today by really high lighting all the various methods students used to answer both the last few table questions and the word problems at the end of the activity.  I asked students to come to the board and script their work and solutions to each question for us and answer questions from their fellow classmates.  The application questions were the most difficult for students to answer and a great opportunity for a quick one question learning check answered on a post-it note and stuck to your door on the way out of class just to see who understands and who does not.