On those weird days, when all the classes are 22 minutes long, or it's a late arrival day and only five students are in class, or 75% of your class has left to watch the state baseball tournament, or the internet is down, or the PSAT / ACT / SAT / PARCC test took way less time than advertised, then it's time for a fun game.
I call this BEAT THE GEEKS.
This ppt contains ten trivia questions (9 rounds on this ppt) about everything from state flowers to movie stars to flag colors.
After each question page, you will find the answers.
I've done this with high school students of all levels, with cell phones allowed and without. I usually offer a few extra credit points to the group with the highest score.
It's fun to have kids work in pairs / groups to try to convince others that they have the correct answer.