You'll be shown a randomly generated circuit and asked a multiple-choice question about its transfer characteristic (the shape of Vout or Iout vs Vin, a slope, or a turn-on voltage). After each answer you'll see the correct answer and the actual transfer-function plots. Your score builds up as you go.
When you're done, click Email results (or Export JSON) and send the downloaded file to Professor Lau. Your progress is saved on this device, so you can come back and continue.