Chapter 10: Classroom Management in the Laboratory
In addition to the guidelines recommended in the Laboratory Safety section, we recommend the following strategies to keep lab work safe, productive, and efficient.
10.1 Set lab rules
Before the first practical of the year, hold a short session to teach lab rules and lab first aid. Try to set a few clear, basic rules – like the four proposed in the Laboratory Safety section – instead of a long list of rules. Post these rules in the lab, and be consistent and strict in enforcing them with students and teachers.
10.2 Train students in basic techniques
For students just beginning laboratory-based education, you can probably teach each specific skill one at a time as they come up in experiments. For more advanced students, especially when they have different backgrounds in terms of laboratory experience, it is wise to spend several sessions practicing basic techniques (e.g. titrations for chemistry, using the galvanometer for physics, etc).
10.3 Have students copy the lab instructions before entering the lab
Do not let them into the lab unless they can show you their copy of the procedure, etc. Have a class dedicated to explaining the practical activity before the actual session. Bring a demo apparatus into the classroom.
10.4 Demonstrate procedures at the beginning
Do not assume that students know how to use a syringe or measure an object with calipers. If there are many new procedures, hold a special session before the practical to teach them the procedures. For titration, for example, hold a practice session in using burettes and syringes with water and food coloring. For food tests, explain and demonstrate each step to the students before holding a practical. It will save you a lot of trouble during the actual practical.
10.5 Have enough materials available
Always prepare 25-50 percent more reagent than you think you will need. Also have spare apparatus in case they fail in use. For example with physics, have extra springs, resistors, weights, etc. That said; do not make all of what you prepare immediately available to the students. As with sugar and salt, an obvious surplus increases consumption. If there is a definite scarcity of resources, it may be necessary to distribute the exact volumes necessary to each student. If you are doing this, make sure students understand that there is no more. In an exam, you might take unique objects, such as ID cards, to ensure each student receives her/his allotment only once.
10.6 Have enough bottles of reagent available
Even if only a small quantity of a reagent is needed, divide it into several bottles and put a bottle on each bench. If the volume is sufficiently small, distribute the chemical in plastic syringes. Do not use syringes for concentrated acids or bases – because these chemicals can degrade the rubber in the syringe, there is a risk of the syringe jamming and the student squirting chemicals into eyes. The waiting caused by shared bottles leads to frustration and quarrels between groups. The last thing you want are students wandering around the lab and crowding to get chemicals.
10.7 Designate fetchers
If students must share a single material source, designate students to fetch materials If a reagent needs to be shared among many students, explain this at the beginning, and have them come to the front of the room to get it rather than carrying it to their benches. This will help to avoid arguments and confusion over where the reagent is. If the students are in groups, have each group appoint one student to be in charge of fetching that chemical. However, it is much better to have the reagent available for each group at their workplace.
10.8 Teach students to clean up before they leave
This will save you a lot of time in preparing and cleaning the lab—and it is just a good habit. Do not let students leave the lab until their glassware is clean and the bench is free of mystery salts and scraps of paper. If they do, consider not letting them in for the next practical. This might take assigned seats if you have many students. When they perform this clean up, make sure they follow whatever guidelines you have set for proper waste disposal.
10.9 Allow more time than you think you will need
What seems like a half hour experiment to you may take an hour for your students. Add fifteen minutes to a half hour more than you think will be necessary. If you finish early, you can have them clean up and then do a bonus demonstration.
10.10 Know the laboratory policies at the school
What is the policy on replacing broken equipment at the school? As a teacher, you need to know what you are going to do when the student drops an expensive piece of glassware. It is no fun to make up procedure while a student is in tears. What criteria will you use to determine if the student is “at fault?” Of course, this is less of an issue if you do not use glass apparatus.