II. Next, students need to decide where on the plant they could accurately count the hairs. It is unnecessary to count all of the hairs on a plant. The number of hairs on one part of the plant appears to be strongly correlated with hairiness on other parts of the plant. [Hint: It may be easiest to count the hairs around the
edge of the first true leaf or on the petiole. This can be done as early as Day 8 or 9 in the life cycle when the first true leaf is well developed (Figure 5)]. Students will need a good lighting source (preferably coming over their shoulder) and a hand lens. By observing the plant against a dark, contrasting background (construction paper, a classmate’s sweater, etc.), it may be easier to count the hairs on the specified plant part.