Kahoot is not brand new in the Ed Tech arena but I recently started using it with my Spanish class. Students are typically engaged in technology but in the years I've been teaching and integrating tech I don't remember anything eliciting a response like this.
I'll admit that I was the first teacher to use Kahoot with this particular group so the novelty was over the top. They were participating, competing, laughing, cheering, and most of all, LEARNING.
Kahoot reminds me of sports bar trivia. (Yes, really.) Questions are posed, and students choose their answers. Points are awarded for correct answers and how quickly you chose your answer. Students can play on ANY device--a huge plus for a BYOD school like mine. Teachers can prepare their own games or choose from thousands of shared Kahoots that can be edited or used as is.
I like that Kahoot lets me download a summary of responses to see how the students answered. Although I don't think Kahoot should be used for formal assessment, it is certainly a valid source of formative data for the teacher.
Kahoot is the easiest and most engaging quick response tool I've used so far.