There's not usually a lot of time to work on the fundamentals of a vinyasa in a class environment as it is better served as a flow but it is a key element of any yoga asana practice so I thought I'd make a little video about it.
Chaturanga is a key element in a vinyasa flow and can be broken down into stages.
Down dog >
Chaturanga/Knees down >
Up dog/Cobra >
You'll need a yoga belt and bolster to work the stages to chaturanga dandasana. And honestly, it's better to work with the knees down than to sink in the back of the shoulders.