Principles for Teaching Science Laboratories
Clarify links between laboratory exercises and course concepts presented in lectures.
Plan lab exercises carefully and work out all logistics. Before you meet students in lab, be sure that equipment is functioning properly and that you have all supplies you'll need.
Allow some lab time for students to do more than "cookbook" work; give them opportunities to think like scientists.
To manage the grading load, break assignments into parts that are due on different dates and provide examples of the types of products you expect students to produce.