The teacher can put their own values of resistor into the circuit using the easy access screw terminals. If there are several boards in the classroom then the students can verify the relationship for several different conditions.
The board strips away the complexity of wiring the circuit and brings Physics to the forefront teaching the relationship between the out of balance resistance and current. AA battery included.
The Philip Harris Decade Resistance Unit is required to operate the Wheatstone Bridge available on code B8L32177.