Classification uses evidence, not just where something lives. A useful feature separates the choices in the key. In our small card set, adult insects have six legs and three main body regions; spiders have eight legs and two main body regions. These rules are not a complete key to all life. Safety: No organisms, field sampling or plant tasting. Stop: Stop at the supplied observations. Do not capture an unfamiliar animal to settle the uncertain card.

Materials: Paper; Pencil 1. Copy five illustrative observation cards: A—six jointed legs, head/thorax/abdomen, two antennae; B—eight jointed legs, two main body regions, no antennae; C—eight jointed legs but body regions not visible; D—green leaves, flowers and enclosed seeds; E—green fronds, spores beneath fronds and no flowers. 2. Make headings Adult insect, Spider, Flowering plant, Fern and Not enough evidence. Put A, B, D and E under the supported headings. For each, underline two card features that support the choice. 3. Compare A with B. Write why legs plus body regions are stronger evidence than the unsupported clue lives in a garden. Compare D with E using their reproductive features. 4. Place C under Not enough evidence for spider identification. Write the next observation needed. Explain why eight legs alone does not distinguish spiders from all other arachnids. Done: The page has four justified placements, one uncertain placement and one useful next observation. Proof: Keep the feature cards and reasons. Record whether the adult pointed out a feature or named a group first. Stop: Stop at the supplied observations. Do not capture an unfamiliar animal to settle the uncertain card.