Adding Mixed Numbers with Unlike Denominators
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Camille Gales Edward Coles Elementary School
8441 S. Yates Blvd.
Chicago IL 60617
This is a seventh grade activity designed to provide students with practice in
adding mixed fractions with unlike denominators.
tape measures; water soluble marking pens; 12 inch rulers; teacher made block
letters of equal height but widths containing fractional parts including 1/16,
1/8, 1/4, 1/3, 1/2 (or any fractional part that can be measured by using a 12
inch ruler); long strips of fadeless paper or a roll of drywall tape; scissors;
Review addition with mixed numbers, first at the board, then at the desk using
individual worksheets. When seatwork is complete pair the students. Using a
tape measure, each student will measure distance from his/her wrist to the tip
of the longest finger. Make a dot, with the marker, at that spot on the wrist
where the measurement began. Record the distance. Next, measure the distance
from the spot on the wrist to the inside fold in the arm where the forearm and
upper arm meet. Put a dot on that spot in the fold. Record that distance.
Measure the distance from the inside fold in the arm to the shoulder joint.
Record it. Sum the three measurements. Measure the distance from the shoulder
joint to the inside fold in the arm. Compare the added length to the measured
In the second activity students will select the precut letters to form such
things as school name, first name or nickname. Students will measure the width
of each letter, allocate 1/4 of an inch space between each letter, and then add
all letter widths and spaces. Once the students have calculated the width of
letters and spaces they will cut fadeless paper or drywall tape to equal the
width of the calculated letters and spaces. Paste the letters onto the
fadeless paper or drywall tape.
In the first activity, if the students have measured and added correctly, the
sum of the three measurements should equal the distance measured from shoulder
joint to finger tip. In the second activity, the length of the fadeless paper
or drywall tape should be equal to the sum of the letters and spaces. Both
activities are self checking.
If the error in measurement is within 1/4 of an inch a grade of A should be
awarded. If the error in measurement is within 1/2 of an inch a grade of B
should be awarded. If the error in measurement is within 1 inch a grade of C
should be awarded. If the error in measurement is within 1 1/2 of an inch a
grade of D should be awarded. If the error in measurement is greater the
activity should be redone.
This activity enables the student to put math concepts to practical use. It
also motivates the student to measure correctly. Finally, the self-checking
mechanism makes the activities easy to grade.