This project definitely takes a couple hours of prep work by me but is totally worth it. Before beginning this project, I cut coardboard into a ton of different shapes such as ovals, triangles, diamonds, circles, etc. I make sure I have a bunch of large body shapes (they are between like 8" to 14") and a bunch of smaller pieces for fins, tails and eyes. If I have 30 students, I make like 35 of each so that they each have a choice. Even with box cutters this is pretty time consuming, but that's ok with me.
The first day of this project, students each go to different piles of the cardboard pieces and play with the pieces arranging them until they have a fish shape they like. I tell each student that they must have a tail and at least two fins. Once they come up with a design they like, they use Elmer's glue all to attach the pieces.
The second class, we begin painting. The tail is one color, the fins are each one color and the body is painted with large stripes. The stripes can go horizontal, vertical or diagonal, whichever they prefer. Some students even do squiggly stripes.
The third class, they use other colors to paint patterns over the stripes. Also, they paint and attach the eye(s).
This is a super quick, super successful project and I will probably do something like this every year (maybe robots next year?)...