Have you ever competed in the "Guess How Much Candy Is In The Jar"? We do it every year at one of the Xmas parties I attend. I have wanted to do this activity with my kids for the past couple of years and I have just put it off. So I was looking for something fun the kids could do after our long winter break and thought, why not, let's go for it.
I started by showing them a picture of candy corn in a jar and asked them how many pieces of candy are in the jar. They were already in. Then I showed them all three jars and told them whatever group in the 7th grade got the closest by mathematically solving it would get all the candy. Smiles all around. I posed the question, "Do you think you can guess closer or mathematically calculate and get closer?" To my surprise most kids said mathematically.
So we dug in. I love starting new projects and not knowing where they will end up. We have learned volume and are pretty good at formulas so that was somewhat review. Since we haven't had school for nearly a month it was good review.
We brainstormed what information we needed (essential questions), then we created a plan on the steps we would go about to solve this problem. This part was just ok. We definitely need some work on this part but it got us started. Next was the fun part. I passed out candy, rulers, and jars and the measuring began. Two of the jars had changes in the sizes so there were two different size cylinders and one was just a straight cylinder. Some groups saw it and some didn't. They measured away.
The challenging part is that the candy corn isn't quite a cone and it is not quite a pyramid. The kids had to analyze and decide which path to take (cone or pyramid) and how to measure it. Then once they divided the jar volume by the candy volume they got the number of pieces in the jar, kinda.
Since the candy corn is filled up the jar with gaps their answers were the first time to big. The kids had to guesstimate the percentage of air vs the percentage of candy. Then as a class we learned how to take a percentage of a number. Finally for the first part the kids wrote a paragraph on why we had to adjust their original answer and their logic on why they chose the percentage they picked.
After all was said and done we calculated that the candy corn took up about 40% of the jar. I melted down a jar full of candy corn and it was very close visually to 40%. The winners enjoyed eating the fruits of their labor, they even shared their winnings with the other kids in class.