Friday, April 3, 2015

Fractions, baking and lowest terms: real-world math

I think that the hardest thing I have encountered in math this year is trying to instil in students the importance of understanding math, not just memorizing rules.  So many times I hear..."I remember doing this last year, but I can't remember the rule".

My message is that if you understand the "why", then there are many different ways of "how" to do it. No rules needed.

Except maybe one.  Lowest terms. ;-)

I decided we would bake.  Cooking is something I try to do several times a year with my classes.  It's engaging, it's a life skill, and it's FUN. Besides, it was the day before Easter Break so baking Bunny Bread was the perfect activity.

I gave students a Bread-in-a-bag recipe. I changed the measurements so that they had to calculate the actual amounts.

Bread in a Bag Recipe
In a one-gallon (heavy-duty) Ziploc bag, mix:

½ X 6/6  cup all purpose flour

9/4  teaspoons yeast

¼ + 2/8  cup warm water

⅓ X 6 tablespoons sugar

Close the bag and knead it with fingers until the ingredients are completely blended. Leave the bag closed, with the contents in the corner, and let rest 10 minutes. You can eliminate this wait by using instant yeast.

Then add:

⅓ x 12/2 cups whole wheat flour

¼ x 2 5/5  cup warm water

5/5  tablespoon vegetable oil

1 1/10 + 18/20 teaspoons salt

Mix well. Add enough all-purpose flour to make a stiff dough, about 1 or 1-1/2 cups. Close the bag and knead it (you may need to remove some air in the bag.) Add more flour until dough no longer sticks to the bag. Spray the hands or food handlers gloves with oil so there will be no sticking. Open the bag and allow the dough to fall out onto clean or gloved hands. Form the dough into a loaf, and place in a loaf pan or onto a cafeteria cookie sheet. Remember the dough will grow 1-1/2 times larger, so leave space between loaves if baking on a cookie sheet. Cover the loaves with oil sprayed plastic wrap and allow to rise 30 (quick rise yeast) to 45 minutes. Bake for 30-35 minutes in a 350 degree oven. Now that’s real world science!  

When they completed the calculations, they began to make the recipe.

EXCEPT, as some discovered, measuring cups don't come in 12th's, nor do measuring spoons have 20th's marked on them.

They noticed that they had to make their answers mixed numbers and lowest terms.

They had a real-world reason to use fractions and to make their answers in lowest terms.

An unexpected spin-off was the mini-inquiry about yeast that the students engaged in. "What is yeast? What does it do? Is it really alive?"

They discovered, by researching while waiting for their yeast to proof, that it is a living organism, and that it requires sugars and heat to grow.  All on their own.

Best of all? They got to eat the results. Bunny bread success!
Ready for the oven.
Baked and ready to eat.

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