For the next part of La Tostada Sabrosa math project, the boys learned about averages and why averaging can be useful.
I gave each of the tostada toppings from our last math session a price and had them add them up to get a price for each topping combination.
Olives 35 cents
Lettuce 15 cents
Salsa 25 cents
Cheese 65 cents
Beans 25 cents
Fried Tortilla 10 cents
Quentin learned how to use a calculator for this lesson because he has already worked on adding double digit numbers but he has never worked with a calculator to solve math problems before.
Next I gave them a lesson about averages. I had Quentin measure the hand spans (the distance between the tip of the thumb to the tip of the pinkie, across the hand) of every member of the family using yarn (as we have made non-standardized measurements before) and then measure them using Unifix cubes.
He taped the yarn pieces to a piece of paper and labeled them according to whose hand span it was and how many Unifix cubes long it was.
We then discussed averages. We took the seven numbers from the seven measurements he took and put them in order from the smallest to the largest, repeating numbers if appropriate. We then made observations about the data. I told him that the amount of difference between the smallest number and the largest number is called the range.
I told James and Quentin about the differences between median (number in the center of the data) and mode (the most frequently occurring number or numbers).
Quentin also determined the average by adding all the measurements and dividing by the amount of numbers in the data. This can be done by comparing the cube trains for each measurement, if the student needs a more visual way of doing this. They can then even out the cube trains by taking some cubes off the longer trains and adding them to the shorter trains until most trains are the same length.
James was able to determine the averages of the tostada costs for tostadas with three topping combinations. He estimated that the average was $1.15, and was pleased that his estimate was spot on.
These averages will be used in future math lessons to determine one standard price for the tostadas.