In order to understand the food web, students need to know the definitions that go along with the different levels of such a structure. Allow students to use the Internet and library books, in groups or by themselves, to define the basic vocabulary needed for an understanding of food webs. Have them look up and define words such as producers, consumers, herbivores, carnivores, omnivores and decomposers. They should also be able to explain each categories relationship to the others.
Ask students to cut out pictures of all of the elements of a particular food web, including the sun. They will attach the pictures to a bulletin board. Ask one student, or a group of students, to come up in front of the classroom and use a piece of string -- or draw a line with chalk -- to indicate one of the connections between the life forms on the board. They should draw or an attach an arrow to indicate the flow of energy. Another student will come up to complete the next relationship.
Ask the students to build a food web online through one of the websites that offer such games. The Chain Reaction game at Ecokids is one such example. Allow the students to work by themselves, or divide them into groups if there are not enough computers for every student. Award a small prize -- such as a no-homework pass or extra points on the food web examination -- to the student who finishes the game in the quickest time with all of the correct answers.
Pass out a handout with a food web on it, except it must be missing at least one element. Ask the students if they can figure out what is missing on the food web. Once they have figured it out, provide another example or two. Now have the students create their own food webs with missing elements. When they have completed this task, collect the webs, mix them up and pass them out for other students to complete.