Ensure that students are prepared. Have students come to lab prepared for the day's activity. This may mean reading the lab manual ahead of time. Ways to encourage students to prepare outside of class may include making a pre-lab assignment due or having a pre-lab quiz. In class, demonstrate unfamiliar equipment prior to asking them to use it. Having prepared students will save much time and frustration during lab time.
Have a plan for organizing lab groups. Don't leave it to chance. You will lose valuable lab time by having students mix around self-selecting groups. Either have the groups determined ahead of time or have a plan to determine the selection.
Make your presence felt in the room. Don't just sit at the front of the class waiting for students to come to you with problems. Circulate around the room, checking on and facilitating student progress. Take an active role, offering assistance and suggestions as needed.
Use mistakes as a teaching strategy. Talk with your students about what went wrong with the lab. Had the experiment gone smoothly, what would the expected result be? What variables could have changed to make the experiment work?
Complete the lab on time. Provide a timeline for completing lab tasks (on the board, for example, write each task and how long it should take). Stick to the schedule whether tasks are completed or not. Try to plan to time at the end of the lab to share results.
Be ready to deal with students who work particularly fast. Have extra tasks or responsibilities on hand, and assign them to students when they finish a task early. These extra tasks should be relevant and important to the class. You may want to ask the student to help others who are lagging behind.
Maintain order with inattentive students. In a lab course, they pose a real danger to themselves and the entire class. Lab safety must be a major concern and clowning around and other distractions could lead to accidents. Students who refuse to comply with safety regulations should not be allowed to continue with the lab.