There are plenty of online quizzes available online that can be used to engage your learners playfully in checking their understanding of the electoral system. Here are some more examples: 

Britannica.com: Republican or Democrat?

Quizzizz.com: Political parties and qualifications

Quizzizz: Electoral process

Howstuffworks.com: The Ultimate Elections Quiz

The Washington Post: The U.S. elections quiz. How much do — and don’t — you know?