My wonderful math students were given a task to help me figure out how to make brownies in the correct size pan. I had 2 recipes. One made only a 8 X 8 pan of brownies and we wanted a 9 X 13 pan. My other recipe was for a 9 X 13 pan but we were unsure if we would like it. We didn't want a big pan if the brownies were not good so we wanted to make a 8 X 8 pan.
Recipe 1: Change our ingredients from a whole batch to a half
Recipe 2: Change our ingredients to double a batch.
The students helped each other figure out how to divide a cup and half flour.
We had a discussion about changing the directions also. How if you double a 300 degree oven to 600 degrees...our brownies would be charred!