I have established a routine with my year three specialised music class.
At the beginning of each lesson we sing an introduction and call and response song as well as singing the solfeggi scale using representative hand signs for each note.
This is an exercise that the students are comfortable with and which I can tailor to become increasingly challenging as their skills increase. A known and liked activity where the whole class is actively participating together gets the students primed for a new lesson. Also, working as a group on something familiar instills confidence in their abilities.
I clearly state what the lesson and objectives are to my students at the beginning of each lesson. I also explaining the relevance of the task to their broader learning and general life. I also brainstorm on what they already know about the topic.
Apart from this, at the beginning of working with a new group I do a group exercise establishing and agreeing on a code of behaviour conduct with the group and which we all agree upon.
It is visible in the classroom and can be referred to when students have behavioural issues contextualising what we have agreed upon and why the behaviour is not acceptable.
Video of my at the beginning of a lesson. Going through can you did that crazy gibberish and scales as well as stating what we are going to do with the lesson and the five l’s.