In this lesson students will be practicing adding and subtracting with unlike denominators. They will be playing a game with a partner to practice this concept and discuss the game as a class.
To begin this lesson I show students a quick video from PBS’s Cyberchase series titled Equal Amounts of Gold. In this quick clip two brothers Pin and Pan are fighting over how to divide their gold evenly. The Cybersquad comes in to help and shows them how equivalent fractions were able to solve the dilemma.
After viewing the clip, we have a discussion centered around the concepts covered within the video. I have provided a series of questions that were available on the PBS website that accompany the video.
What did the CyberSquad know about these fractions that helped them share the gold equally between Pin and Pan? How did they decide which gold bars represented which fractions? For example, how did they know the bar they called one-fourth, was really one-fourth? Draw a diagram showing the equivalencies between eighths, fourths, halves, and a whole.
To practice adding and subtracting fractions with unlike denominators students will be playing a game called Up and Down the Number Line. I found this game in the Georgia State curriculum. Pairs of students will need a game board, counters and a spinner. There are two game boards provided in the directions of the game but I suggest starting with the game board that is labeled all in sixteenths.
The object of the game is to get to either one or zero(MP 1 and 6). Both players start at 1/2 and then have to spin to determine how much they will add or subtract to 1/2. One player is going to one and the other player is going to zero. If the spin received makes either play go past their target then the player has to go the opposite direction the amount spun.
Partnerships can take turns going for the target of one or zero. The second game board only makes things a little more difficult because it is labeled with equivalent fractions instead of all sixteenths.
To wrap up this lesson and the Up and Down the Number Line game, I bring students back to the whole group for a discussion using the formative assessment questions from the activity. The questions are as follows:
What fraction would you like to spin first? Why?
What strategies do you have for this game?
If you could change the spinner what fraction would you like to have on it?
Did you notice any relationships between any of the fractions?