Padlet - Let the students respond to prompts through the written word. This gives every student a chance to express themselves without having to wait their turn or being embarrassed to speak in front of others. Responses can be printed off for a quick check for understanding later.
Quizzizz - Fun, engaging activity that students play independently and see how they rank against the rest of the class. Can be timed or not so that you can win based on correct answers AND time, or just correct answers.
Kahoot - Similar to Quizzizz, but the players can be a team or individual. The points assigned to responses is timed which puts a little more pressure on the players.
Today's Meet - This allows students to ask a question as soon as they think of one without interrupting the flow of the lesson. The teacher can monitor the questions and comments and determine when they will answer the questions/comments, but other students have the opportunity to respond as well.