These tasks will mainly involve the content of the named skill and be specific to that skill. However, also included in each one will be some questions on topics already covered to provide continued reinforcement and further practice.  As more topics are covered throughout the year,  it allows those to become part of another homework specific task. 
The mixed skills homework tasks are non-specific, and mimic mini assessments as you are required to establish what is being asked.  They will involve a mixture of at least 5 topics.