"Art lesson would be one that produced diverse outcomes, not identical ones, so always offer children choices. Encourage them to make decisions about the scale on which they work, the materials they use, even whether they want to work alone or as part of a group."
I have successfully implemented over a dozen of art lesson plans to students with a diverse background and demographics in numerous settings for over 18 years.
I began my art lessons with a brief introduction on the art lesson, demonstration of the art lesson and rules for ethics during the art lesson.
For example, the below art lesson is designed for students specifically preschoolers and elementary school students. Students learn how to use their fine motor skills to create interesting mask cuts to create wonderful mask collages using creativity, paper, glue and scissors.