Developing test instruments for the Pattern Drills Program in the Pittsburg Public Schools has convinced the writer that the more test development activities and the teaching process reinforce each other, the stronger the program is. The Pattern Drills Program aims to develop bidialectism in non-standard English speakers by teaching standard English as a foreign language. The Drills reinforce and provide for "eventual automatic control of the standard pattern" by substitution practice. The contemporary psychophysics approach, described by Galanter in 1962 in terms of "detection,""recognition,""discrimination," and "scaling," can be used in testing for language development or for teaching language development. One reason for failure in teaching "correct standard English" is inappropriate measures. If a child cannot speak standard English at the appropriate time, we need to know whether it is because he cannot hear the difference, cannot mimic the difference, does not know the difference between different situations, or whether, although he has acquired all these "components," he just cannot combine them. Knowledge of this information would definitely have an effect on how we teach. (AMM)