Frugal Freda's Fruit Foray

Task

I am always looking for tasks that call students to practice the use of fraction/decimal/percent conversions. We discussed in science class the definition of fruits and in home economics students had been considering smart consumer choices. I thought the students would have a good time with this task and would have the opportunity to practice lots of mathematics skills. I found this to be true.

What This Task Accomplishes

There was an immense amount of mathematical calculations in this task. Students had to find the weight of each fruit, with and without skin. They had to compute the price of each piece of fruit, given the price per pound. Some of the balances were metric and that called for making ounce/gram conversions. Students then had to compare the price per serving of the four fruits, having examined the results of their measurements, as well as those of the other groups. There were many opportunities for decision making throughout this task.

What the Student Will Do

Each group was given a navel orange, tangerine and a banana. Due to the price of cantaloupes, each class had one and had to decide what constituted "a serving" of the melon. They found the mass of the fruits, peeled and seeded them and found the mass of the peeled fruit. They calculated the edible percentage of each fruit and recorded that on the class list. There was a class discussion of the reliability of the data, as well as the range of results. Students were given the price per pound for each fruit, and they had to calculate the cost per serving of the actual amount of edible flesh and compare these costs. Their advice to Freda was interesting. The cost per serving of bananas and oranges was very close, so she should consider factors other than mere cost in making her decisions.

Time Required for Task

We were able to do the actual laboratory aspect of this task in 60 minutes.

It took the students about one-in-a-half to two hours to complete the calculations and do the write-ups.

Interdisciplinary Links

This fits well in a life science plant unit as you study fruits. It is also a good connection to a home economics study of consumer decision making, diet considerations and unit pricing. Getting the health educator to discuss nutritional aspects of these fruits at the same time would ensure that the students could advise Freda with considerations other than simply price alone.

Teaching Tips

Providing students with bowls and plastic knives helps them to hang on to the juice, seeds and scraps, as well as the edible fruit.

Suggested Materials

• Fruit - one of each per group


• Navel oranges (Californian are best), tangerines and bananas


• Melon - one per class


• Bowls and knives - one per group


• Balances - one per group


• Calculators


• Graph paper

Possible Solutions

According to my calculations, the cost per serving of each fruit was:

Bananas = $.057

Oranges = $.059

Tangerines = $.073

Cantaloupe = $.105

Because bananas and oranges are so close, Freda might want to consider Vitamin C or Potassium content of each fruit. She might want to think about calorie content as well. She also might consider whether she will be eating the fruit at home, where she can wash off the juice, or on the road where the banana might be easier to peel and neater to eat.

Benchmark Descriptors

Novice
This student shows no mathematics in this task. The weighing and peeling were done in class in groups and this student seemed to have missed the point. His/her advice to Freda shows no evidence of mathematical reasoning. "Looking and feeling for the greatest amount of flesh" replaces providing mathematical evidence for decision making.

Apprentice
This student missed the fact that all the prices of fruits were posted in the front of the room from the onset of the assignment. S/he never answers the question about what fruit to buy. S/he does not carry out the mathematical procedure needed to advise Freda (getting to a common unit price for the edible portion of fruits). There is some correct notation e.g. %, an attempt at representation. Explanation is incomplete and not clearly presented.

Practitioner
The solution shows that the student has a broad understanding of the problem and the major concepts necessary for its solution. The student uses a strategy that leads to a solution to the problem. There is effective mathematical reasoning. Appropriate mathematical procedures were used. The explanation is clear except on the bottom of page one. The representation is good. There is solid math language used throughout the solution.

Expert
This student identified appropriate mathematical concepts and information necessary for a solution. The strategy is very efficient leading directly to a solution. S/he shows refined reasoning and a succinct presentation. The reader does not need to infer anything as the solution is clearly stated. The representation makes use of technology and clearly communicates the solution. There is precise and appropriate mathematical terminology and notation.