Consider to the circuit shown. You surely recognize the basic circuit from the Experiment 8.
Once you push the pushbutton switch S1, the LED2 lights up. After a switching time T of approximately 2.5 seconds, LED2 goes out and LED1 lights up again.
In fact, you can calculate the approximate switching time T...
T = 1.1 × R2C1
= 1.1 × 22,000 Ω × 0.0001 F = 2.4 sec
What happens if you press the push-button switch repeatedly?