The lack of code comprehension skills in novice programming students is recognised as a major factor underpinning poor learning outcomes. We use Schulte's Block Model to support teachers' understanding of how to break the skill down into component parts that are more manageable for a learner. This analysis is operationalised in three code annotation-based learning/assessment exercise formats, two helping students to identify and describe programming concepts and the third enabling them to parse code correctly and carry out desk executions. A great benefit of the activities is that they are low cost and can be applied to any imperative style code and so can be easily adopted by schools anywhere; furthermore, they are active, not passive, an issue with some animation-based visualisation approaches. The exercise formats were included as part of a national schools computing science professional learning programme (PLAN C).