Whilst working with the circuits in Fig. 4, the students’ commented: ‘We have examined the wires and tried to create the circuit on the screen.’ After few changes Circuit 1 was created. ‘Then we checked what happens when both switches are open and it worked like the real circuit. We closed only one switch, then only the other, and it was identical. We thought that we got the correct solution then when we closed both switches bulb A lit in the real circuit but not on the screen. We did not understand what is wrong and at the beginning we thought it might be a bug (in the simulation). Then we saw there is no current (arrow) on bulb A and we realised that all the current goes through the switch because is connected in parallel. To avoid this, we connected SA to the other side of bulb C and it worked like in reality.’ This process took about 20 minutes.