Ratio, Percent & Proportions

Rosalyn Winston                Walt Disney Magnet School
                               4140 N. Marine Drive
                               Chicago IL 60613
                               (773) 534-5846

Objectives:  
               
To write fractions as percents for seventh graders.
To find the percent of a number.
To find percents using proportions.
To calculate the weight of objects (beads) in grams given specific percents.
To verify the weight of objects (beads) on a scale in grams in cooperative
   learning groups.

Materials Needed:

calculators
electronic scale measures in grams and ounces 
clear plastic liter bottle
clear containers for each cooperative learning group
multi-colored chalk or overhead transparency markers
containers to hold objects 
beads of various colors

Strategy:


 "The phenomenological approach to mathematical instruction asks a question
which requires the use of mathematics to answer it.  The question must be based
on a physical entity present for observation and use the mathematical processes 
you are teaching at the time.  The answer to the question must be verifiable by
direct observation." 

How much will the beads that each person has weigh?  Four cooperative group 
members are sitting around a pile of beads weighing 237 ounces.  The first 
person takes 4 beads from the pile, the second person takes 3 beads, the third 
person takes 2 beads; the fourth person takes 1 bead from the pile.  They 
continue the process until all the beads are gone.  Each person now holds a 
percent (10%, 20%, 30% or 40%) of the original pile. 

Each cooperative math group will do their calculations first.

The total weight of all the beads is 237 grams.  The first student should have
130 grams.  40% of 237 is 130.00 grams.  The second person should have 30% of
237 grams or 71.10 grams.  The third person should have 30% of 237 grams or 47.4
grams.  The fourth person should have 23.7 grams or 10% of 237 grams.

Check each individual's calculations.
Verify each individual's beads weight on the electronic scale.

Performance Assessment:

Give the cooperative math groups different bags of beads to calculate weight 
with the same percentages 40%, 30%, 20%,10% or, give them new percentages to 
investigate.