Kahoot allows one to gauge the overall comprehension a class has for the subject through quizzes and surveys. Kahoot gamifies the classroom experience and offers a different way to engage with the content.
Create a variety of question/answer options including multiple choice, word cloud, open ended, and more. Free version is limited to presentations with only 2 questions
Edpuzzle allows one to edit a video and to add content to the video, including the ability to have the video pause while the student responds to a question.
Pear Deck allows one to create a live slide-deck session that students can join. Pre-planned and impromptu questions can be asked throughout the presentation.
To utilize Plickers, only the instructor needs a device (iOS or Android). Students respond to questions using cards, which are then scanned and captured by the app.