We can use them at any level but there are a lot of kind of warm ups depending on it. there are specifics warm ups that are for basic, intermediate or advanced levels.
It's very nice to be part and at the same time a presenter of a warm up activity because you learn, coexist and work with the classmates. As a presenter you have the responsibility of direct them because you are like the role model of them and if you make mistakes they are not going to understand you or they are going to do the same as you.Therefore; being a presenter is difficult because you must give instructions as clear as possible.
I felt nervous because i was going to be the teacher in that moment so that meant i was going to have the responsibility of a whole class.
A warm up it is not just a funny activity. I think that you learn from any kind of warm up; futhermore, some of them play with your mind and test how much you know. In my case as a presenter, i knew that i had to give instructions in a clearer way. but the next time i'm going to do it better. in some cases is necessary to start a class with a warm up, but it depends of the subject and what you want to teach with the activity because in sometimes you have to provide energy to your class.
To sum up , it's nice to test new activities and break the routine and at the same time you can know what your students are able to do and know different kind of multiple intelligences they can have.