Think you have a good sense of timing?
If you're not sure, here's a Project that will let you quickly find out.
A quick glance at the schematic shows this Project uses both a J-K flip-flop and an astable multivibrator. The astable multivibrator will produce a sound from the Speaker and you'll also notice LEDs 1 and 2 light up at different rates.
Both the SW1 and Select Switches are used here to control the inputs to the J-K flip-flop circuits. Your job is to select that combination of switch settings that will let both LEDs light and also produce a sound from the speaker.
Now set the Select Switch to A to generate pulses for the J-K flip-flop. You'll now hear sounds from the Speaker and LED 1 and 2 will flicker.
Now try setting both the SW1 and Select Switch to different positions. If you
manage to set the switches to the correct positions at the right time you'll
light both LEDs and hear a sound from the Speaker.