#236. Fraction Sandwiches

Mathematics, level: Middle
Posted by Kaleb Allinson (kaleb@cc.wwu.edu).
Western Washington University, Bellingham, USA
Materials Required: fraction bars (not neccessary)
Activity Time: 20-25 Minutes
Concepts Taught: Adding and subtracting fractions

Adding and Subtracting Fractions
By Kaleb Allinson
http://www.wwu.edu/~kaleb

This classroom is right under 30 students and they are in 7th grade math.

Students will be able to find the common unit of measure, or the common denominator, and will show this be correctly adding fractions with different denominators.

45 Minutes is the approximate class time.

10 Minutes: Simple sandwich problem and discussion of common units.
10 Minutes: Introduction and meat of fractions and common units.
20 Minutes: Work with fraction pie manipulatives to solve new sandwich problem.
5 Minutes: Work on homework.

Sandwich Problem
These students come to school with fractions of their sandwiches.

Did they eat them on the way to school?
Name Amount of Sandwich
Jeff 1/3
Jennifer 2/5
Jessica 2/11
Julia 3/12
Jonathan 7/8
Jacob 3
Jill 2
Juan 6/7

How many sandwiches do Jessica and Jacob have together?

How many sandwiches do Jeff and Jennifer have together?

How many sandwiches do Jonathan and Jeff have together?

How many sandwiches will Jill and Juan have together if they give ½ of a sandwich to a friend?

If Jeff and Jennifer give away 2/3 of a sandwiches from their total, how many will they have left to eat?

How many sandwiches do Jennifer and Juan have?

How many will they have if they give 2/3 of a sandwich to Jeff so that he will have one whole sandwich?

If the students combine their sandwiches will they have enough to each eat one whole sandwich?