Divide the class into teams of eight students each. (Groups may be larger or smaller, if desired, but they must be at least five students each.)
Have all the students stand in a circle.
Distribute a ball of string or yarn to one member of each group. This person represents the sun and starts each food web.
Have the first student hold tightly to the end of the string and toss the ball of string to another person in the group, across the circle.
Have the second person name one thing in the ecosystem that uses energy from the sun. Next, have this person clasp the string with one hand and toss the ball of string on to another student in the circle with his/her other hand.
Have the third student name something that eats or is eaten by the previous item named.
Continue until all students in the circle are connected with the ball of string at least once.
Have the student groups stop and look at the web they have created. Are some webs more complex than others? Why? (Answer: Some species may have been named twice because they are consumers of multiple things; some ecosystems have more variety of food sources, etc.) Point out to students how they have modeled a food chain or food web.