**Lesson for Multiplying and Dividing Fractions with Post It Notes**

Robert Foote Disney Magnet School

4140 N. Marine Drive

Chicago IL 60613

(773)534-5844

**Objectives**:

Students will use postit notes to measure various dimensions of rectangles to

nearest fraction of an inch. This lesson is intended for seventh grade.

Students will divide fractions to predict the number of postits needed to meet

the length and width of the rectangles.

**Materials Needed**:

3 by 3 inch postit notes

1 1/2 by 2 inch postit notes

different sized rectangular shaped paper

rulers and yardsticks

**Strategy**:

Show students a piece of 8 1/2 by 11 inch piece of paper. Ask students how many

postit notes it would take to meet the length and width of the piece of paper of

each size. Explain the algorithm for dividing fractions to see mathematically

how many 3 by 3 postits will fit and how many 1 1/2 by 2 will fit. To

illustrate this, divide 8 1/2 by 3. You get 2 5/6. Take the 3 by 3 postit

notes and place them along the 8 1/2 side of the paper. Carefully cut the

overlapping part of the last postit note. Measure the part remaining on the

paper and it should be close to 5/6 of 3 or 2 1/2. Measure the part you cut and

it should be 1/2. Do the same procedure with the other dimension of the 8 1/2

by 11 paper by dividing 11 by 3. Place the postit notes along the 11 inch side

and verify the math. Then do the same with 1 1/2 by 2 inch post it notes. After

finishing this demonstration, pass out two different size rectangular sheets of

paper and have students measure the sides. Working in groups, have students

determine mathematically how many of each kind of postit notes it would take to

cover both dimensions of both sheets. The students, after doing the math, will

then tell you how many postit notes they need. Give them exactly what they ask

for and have them cut out the fractional part of the post it note they need by

measuring it first. Display the student's work on the board and discuss

strategies for finding the answer and ways the answer could go wrong. Precise

measurement is very important for accurate results.

**Performance Assessment**:

This activity in itself is a wonderful performance assessment. You may modify

the sizes of the rectangles or simply use straight lines.

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