Bring a nest that has been used by a family of birds into the classroom. Discuss with the children the different materials that birds use to build their nests. List the materials on the board. Allow the children to examine the nest carefully, using a magnifying glass if possible. Ask them to add other materials that they find in the nest to the list. Working in a place where all the children can see you, deconstruct the nest with a pair of tweezers. Allow the children to guide you in placing each material you pull from the nest into a separate classification pile. You could create two piles, one of "natural" building materials such as grass and twigs, and one of "man-made" building materials such as string and foil.
Provide your classroom a selection of nest-building supplies such as mud, straw, grass, twigs, string and sticks. Divide the students into small groups and have each group select the building supplies with which they will work. Draw an image of a finished nest and post it at the front of the room where the children can see it. Ask them to use the shape you have drawn as their guide for creating their nests. Set each group's nest aside to dry. Once the nests are dry, have each group present their nest to the class, explaining why they chose the building materials they did.
Read the English fairy tale "The Magpie's Nest" by Joseph Jacobs to your students. This story explains the nest-building steps a magpie takes to build her nest, while the other birds such as a blackbird, owl and starling visit her to comment on her nest-building process. The magpie tries to help the other birds learn to build a nest like hers, but is finally discouraged and refuses to help anymore. This tale attempts to present an explanation of why different birds build different types of nests. Talk with your students about the different personalities of the birds in the stories, and how these might be reflected in the sorts of nests each type of bird might build.
Clear a classroom bulletin board and ask the students to bring in pictures from home of different bird nests. Encourage them to look through magazines and on the Internet with their parents for pictures of bird nests. Ask them to make sure to label the pictures they bring in so they can associate each nest picture with the bird that built it. Have each student present a couple of the nest pictures to the class, describing what the nest looks like in the picture and which bird created it. Create a collage of bird nests on the bulletin board, labeling each nest with the name of the bird that built it.