Before young students can classify insects, they must know what insects are and how they differ from similar creatures. Introduce your children to insects by asking them to describe an insect's characteristics. Have your children create a list of insects and creatures they think might be insects. Have them then search for pictures of the listed creatures on the Internet if available, and in encyclopedias, books and magazines. Encourage your children to examine each picture carefully. Remind them that insects have an external skeleton called an exoskeleton rather than bones, and that their bodies consist of three parts: the head, the thorax and the abdomen. Point out that insects have exactly six legs. Creatures that don't share these characteristics are not insects, so student should remove them from their lists.
Scientists have identified about one million insect species, but there may be as many as 30 million species of insect. Entomologists divide insects into approximately 31 groups called "orders." The scientists place insects into these orders based on various physical characteristics. For example, flies and other insects from the order diptera have two wings. Grasshoppers, crickets and other members of the order orthoptera have hind legs adapted to jumping.
Help your students understand how entomologists classify insects by creating classification cards. Create several picture cards featuring insects. Then create a second set of cards featuring statements about insect anatomy, such as "sucking mouth parts" or "winged insects." Create enough picture cards to classify at least two insects in each category. Lay the picture cards face up on a table and the statement cards face down. Have your students take turns picking statement cards and matching them with pictures that fit that statement.
Collecting insects is a hands-on way for children to become familiar with the different orders of insects. Relatively intact dead insects are often found on car grills, window sills, pathways and roadsides. Some living insects can be caught with tweezers or forceps, while others can only be caught with nets or traps. Once live insects are caught, they must be killed in a killing jar made from an old peanut butter or mayonnaise jar containing a cotton ball or crumpled tissue paper soaked in a poison such as rubbing alcohol. This should be done by the teacher, without the students handling or coming into contact with any poisons. Once the insects are dead, the children can use a magnifying glass or microscope to get a closer look at the insect's parts.