Whoa! I have two fish in my aquarium. Betty, my white goldfish always stays really close to the front wall as she swims towards her food. However, Stripe, my striped goldfish swims diagonally across the tank to the back top right to retrieve his sprinkle of food.

I wonder which fish swims a greater distance? How much longer a trip does Stripe take? What information do you need to find out?

Check out this blogpost write up of this activity by a math teacher and blogger, Martin Joyce.

Extension: Once you figure out which fish swims a greater distance think about how much faster that fish has to swim compared to the other fish in order to get to the food at the same time?

The Activity: fish-tale.pdf

For members we have editable Word docs and solutions.

fish-tale.doc fish-tale-solution.pdf

CCSS: 8.G.7, HSG.SRT.C.8

Thanks to Brian and everyone else at Yummy Math for making this lesson.

My students were engaged and rose to the challenge for the most part. I will teach this lesson now every year to 8th graders in hopes that I can refine it with better pocket questions so low students can have more success.

I wrote up a summary of my experience teaching it with student samples at: http://goo.gl/4wIhMY .

I believe there is another way to answer the problem. Could the students not form a right triangle by using Betty’s distance of 30 inches and then use the 10 inches? This also gets the answer of 31.6 inches.

Many thanks to Colleen Pauley Perry and her 8th graders in Tampa Bay, Florida, who let us know that a Clown fish and a Goldfish couldn’t live in the same acquarium.