1. Treasures from the Attic
Chapter 2: Addition & Subtraction with Fractions
M
3
In the Balance
Lesson 2
Mrs. Matthews/CES
2. Objectives
To develop a variety of methods for adding and subtracting unit fractions with like and
unlike denominators.
To construct algorithms for adding and subtracting unit fractions with like and unlike
denominators.
4. While looking through the old things from the General Store in the attic, Tori and Jordan found an old
balance scale and some weights. The weights they found were one weight for each of the following
amounts: 1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/7, 1/8, 1/9 and 1/10 of a pound.
At first they thought that several of the weights must have been lost, but they also found a note in the
books from the store that these were the only weights that they had. Grandma said that her grandparents
told her that these weights were used to measure all the amounts of candy, cheese, meat and other things
that had to be weighed for the customers in the general store.
5. Find a way to measure 3/4 of a pound of candy using only the weights Tori and Jordan
found.
Discuss how this might be done.
Here are the weights they found:
1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/7, 1/8, 1/9 and 1/10 of a pound.