in their longitudinal investigation, Chess and Thomas found that 40 percent of the children they studied could be classified as easy, 10 percent as difficult, and 15 percent as slow to warm up. notice that 35 percent did not fit any of the three patterns. researchers have found that these three basics clusters of temperament are moderately stable across the childhood years. a difficult temperament, or a temperament that reflects a lack of control, can place a student at risk for problems.
another way of classify temperament focuses on the differences between a shy, subdued, timid child and a sociable, extraverted, bold child. Jerome Kagan regards shyness with strangers as one feature of a broad temperament category called inhibition to the unfamiliar.