We made a food web on a blank wall. A food web is simply a bunch of food chains that connect with each other. So, both a snake and a cat might eat a mouse so we connected (using yarn) the mouse sign to both the cat and the snake. The cat might also eat a bird, so there's a string going from the cat to the bird. The bird eats both seeds and worms, so there are two more strings.
I played a game to see how energy transferred through the food chain by playing tag. There are three or more kinds of animals, cougars, plants, and deer. It is like taga and paper rock scissors. If a deer touches a plant, the plant becomes deer, cougars catch deer, and plants catch cougars (everything becomes part of the earth when it dies). Stop occasionally and tally what you are and you can graph it later. Kids like playing it, and it can lead to food chain, energy chain, etc...
When I did my food chain unit this year I did an activity where the kids used small paper plates (the cheap kind that are sold in bulk) to make a vertical "chain".
They were given four plates each and had to draw and label (from the bottom to the top):
A primary consumer (herbivore)
A secondary consumer (carnivore)
I stapled the plates together vertically, but for those who have more time and patience, punching holes and stringing them together would be great!
Since the guidelines allowed them to choose their own animals, they were able to get creative. Also, it forced them to think about what animals co-exist in specific ecosystems. I had children that wanted to use a zebra and a shark in the same food chain. I made them re-evaluate the herbivores and carnivores that live in one single ecosystem.