This activity can be done by individual students or in groups (competition-based).
Peer instruction, pioneered by Eric Mazur (Harvard), is recommended to be incorporated in this activity. To do so, first, allow students to answer the MCQs individually. After all responses are submitted, ask the students to discuss with their neighbours in class before answering again.
There should not be an overwhelming amount of questions asked in each class. One strategy is to ask a polling / clicker question after a new concept is introduced such that students can apply their knowledge. Another alternative is to introduce a new concept with a polling / clicker question to motivate learning.