I can't believe we are over half way done this book! I feel like it is a fairly quick read yet I have some great information to take back to the classroom with me in the fall.
The posting schedule for Beyond Pizzas & Pies (all Wednesdays)
June 10th Chapters 1&2
June 17th Chapters 3&4
June 24th Chapters 5&6
July 1st Chapters 7&8
Chapter 5: Is 1/2 Always Greater Than 1/3?
"Our research suggests that many students did not understand that, within a context, the size of the wholes must be determined before comparing fractional quantities."
This quote from chapter 5 really sums up what I have seen over and over again with students and teachers. When I learned about fractions in elementary school, I can't recall a single time where we solved a problem about fractions where the wholes were not the same. Even now, when companies send me various curriculum samples, many of them do not contain any problems in which the wholes can vary. I think a lot of the issue with kids not understanding that the size of the wholes must be determined is that they don't get a chance to see a lot of problems where the size of the whole might vary.
In my school, we have a long standing tradition of introducing the ideas of the size of the wholes with Hershey bars. A good teacher friend of mine came up with this many years ago when we were co-teaching a fifth grade. Now I do this lesson in grade four. I get two paper bags and some candy bars. One bag contains regular sized Hershey bars (the ones with 12 small rectangles). The other bag contains the smaller Hershey bars. Here you can either use the minis or the small ones with 4 rectangles that often come in an 8 pack at drug stores and supermarkets. I then hold one bag and have another person hold the other bag. Then I ask, "Who would like a chocolate bar? Mrs. ____ and I have chocolate bars in these bags. I will be giving out whole chocolate bars and Mrs. _____ will be giving out a half of a chocolate bar. Please raise your hand if you want a whole chocolate bar and I will come give you one." Most or all of the kids choose the whole chocolate bar which of course means they get one of the small ones. If no students choose the half, I will "run out" of whole bars and one kid will have to settle for half of one. When it is reveled that the kids who is getting half actually gets more, many kids are shocked but I think it leaves a big impression about making sure you notice the size of the whole.
Does your curriculum include lessons about the size of the whole or ask questions where the two wholes vary in size?
Chapter 6: How Come 1/5 is Not Equal to .15
Two activities I added a few years ago when we stopped doing the probability unit that I think can be really helpful and are very similar to the double number line lesson presented in this chapter are the Meter Stick Number Line Lesson and the 100 Bead String Number Line Lesson.
How do you make sure your students have a good understanding of how fractions and decimals relate?
Looking forward to reading your responses in the comments below!