Simple panel,  with 4 MES lamps that can be arranged in series connections.    Small switches are used in various positions.

Any MES lamp can be used of varius voltages but typical lamps can be 1.5 or 3V and say 50 to 100mA.   It is the choice of the teacher,  but to show changes in brightness in either series or parallel connections,  it is best for all the lamps to all be the same rating or comparing the brightness becomes meaningless.  

Although they are more modern,  LEDs are not used because they do not change brightness with the same certainty as filaments in lamps.

Brand : IEC