math and science education math stories

click here for a printable student worksheet of this challenge

Lesson: The Pen Problem
Grade Level: 2-3
Lesson Aim: use grid paper to graphically represent how to make change of a dollar.  

For your birthday, your uncle who lives in (your favorite state here)                 has sent you a $1 gift certificate to the Famous Pen Shop in New York. You have enough to buy one of these three pens. Which one would you buy, and how much change should you get?

A

26¢

B

27¢

C

28¢

Notes:

After students choose which pen they will buy, they choose a color for the money spent and shade the appropriate number of boxes on the hundreds grid (see below). The remaining boxes are shaded in using a different color so that the change and money spent are graphically shown.
Encourage students to use their knowledge of tens and ones to determine the amount of change. Discuss how to count units (boxes) to the next higher ten, and then count by tens to one hundred. (see example)

Change of a Dollar Chart:

spent      change

 

 

   

This chart represents the 28¢ cent pen with 72¢ change.

Students count the 2 boxes to make 30, and then by tens to one hundred to arrive at 72

 

                 
                   
                   
                   
                   
                   
                   
                   
                   
                   

Challenge:
If you decided to buy two pens, which two would you buy, and how much change would you get for your $1?

Challenge 2: How much change would you get if you bought all three pens?

Super challenge: If you bought two of each of the pens, and paid with a $5 bill that your uncle gave you, how much change would you get?



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