From the teaching standpoint in general physics, the pendulum clock uncompensated for temperature change continues to offer valuable material. The present discussion emphasizes that although the oscillation rate is affected by thermal expansion or contraction, causing the clock to “lose” or “gain,” the behavior of the clock remains perfectly normal, that is, “correct,” controlled by physical laws. Consequently, the terms “correct” and “incorrect” should not be applied to period or temperature, but such terms as “standard” or “nonstandard” substituted for them. Attention is focused on the sharp distinction between indicated and actual elapsed time, withindicated seconds per vibration, a constant of the clock, as the key to a clear and general analysis. This constant equals the period only at the standard temperature.