TABLE OF CONTENTS
Teaching students about lab safety and the safe handling of chemicals and lab equipment goes beyond just teaching the lab safety rules. It's about students learning how to make good decisions in the laboratory and conducting essential risk assessments for every practical. In the high school science lab, students are excited to conduct new activities and want to mix chemicals so something can go BOOM! In this new and mysterious space, the likelihood of injury and accidents is high.
I cannot count the number of times when starting off the school year, in spite of my explicit instructions, one student takes it on their own to mix up all the chemicals on the bench to see what would happen. I even once had a student develop a severe rash all over her body after spilling then trying to hide some substance she found on her lab bench.
Chemistry and other physical sciences are demanding subjects to teach due to the potential hazards that exist. An emphasis on lab safety is paramount, to ensure classes run smoothly, and incident-free. It is imperative, in high school laboratory settings especially, that students are taught what can go wrong, preventative measures and protocols that need to be followed in case of an emergency.
Duties of the science teacher
Science teachers have an obligation (by law) to protect the students in their charge from unreasonable risk (NSTA 2014 a). According to Science classroom safety and the law: A handbook for teachers : “A breach of a particular duty owed to a student or others may lead to liability for both the teacher and the school district that employs the teacher (Ryan 2001).
Science teachers' main duties include:
The duty to provide adequate instruction
The duty to provide supervision at all times.
The duty to ensure maintenance of equipment used in the school laboratory.
Ideas for the classroom
Some aspects of lab safety will require direct instruction which is usually the route taken with younger students (ages 11-14). Activities such as the creation of lab safety posters, role-playing, the assessment of lab safety scenarios where students identify safe and unsafe practices are useful and engaging activities.
You can even use games, interactive quizzes, puzzles, etc to make learning
more active while also teaching students the importance of maintaining a safe laboratory environment. The lab safety Dominoes is a useful and minimal prep activity that can be used for teaching students their lab safety symbols and precautions.
With older students (ages 14-16), lab safety should be more contextualized, and should be incorporated into student practical work. At this stage, students should be able to match precautions to potential hazards present in the laboratory procedure they will be conducting.
For example, students can be asked to assess the risks of a particular activity, analyze MSDS data sheets, choose the appropriate apparatus to complete certain tasks, have discussions about the precision of measuring instruments, and proper and safe handling of equipment.
Preparing for Laboratory Activities
When preparing for any practical activity which involves the use of chemical substances and/or heat, you should consider the following:
You should have a basic understanding of all the potential hazards that can occur with the use of equipment and material.
Use Safety Data Sheets to weigh the potential risk factors against the educational value of each practical activity.
If you are not comfortable with your students handling certain chemicals or equipment (and you do not have a lab tech or aid to assist you) you may consider performing the activity as a demonstration, virtual lab, or simulation. PHET has wonderful and interactive science simulations that can be utilized for online learning. These simulations can also be modified for face to face instruction
Inspect all equipment/ apparatus for defects prior to use.
You should also regularly check that the safety equipment meets the health and safety standards of your state/district. If you encounter any issues/ defects it is imperative that you file a written report for maintenance or correction in order to avoid liability.
Discuss all safety concerns and potential hazards with your students prior to every laboratory activity.
Explain in detail the consequences of violating these safety rules and procedures. It would be advisable to also provide students with the relevant MSDS information along with the lab procedure prior to the practical activity. You can use Google Classroom™ to post lab information and a short pre-lab quiz using Google Forms ™ . This way you can track who has read the lab safety protocols. Completion of pre-lab quizzes can also account for a small percentage of your term grade.
What students need to Know
In addition to adequate preparation prior to laboratory sessions, you should place emphasis on the following in your lab safety plan:
The Importance of Personal protection
Emphasis should be placed on the use of personal protective equipment when performing lab activities. Students should be made aware that dressing appropriately for the lab does have an impact on their safety. This includes:
The use of a lab coat/apron made from 100% cotton or flame-resistant material. This should cover their torso and their upper arms. They should also be encouraged to dress appropriately for every lab session including long pants, closed-toed shoes, and long-sleeved shirts.
Splash-proof safety goggles, which should be worn at all times. Students should be encouraged to wear these even over their prescription glasses. Also, the use of contact lenses should seriously be discouraged.
Long hair should be tied up and jewelry, as well as cellphones, should be left in bags or lockers.
Location and use of Lab safety equipment
Both you and your students should know the location and proper use of all the safety and emergency equipment in the laboratory. You should print out a floor plan of your laboratory and have students label on their plan the location of each of the following:
Fire extinguishers
Fire blanket
First aid kits
Safety shower
Eyewash station(s)
Emergency exits and evacuation routes.
I have prepared a checklist of lab safety and emergency equipment and guidelines to follow in case of a chemical accident based on the recommendations of the Council of State Science Supervisors in science. These can be printed and handed out to your students.
Hazards associated with different chemicals
The hazards associated with chemicals are classified according to the UN Globally Harmonised System (GHS). These signs and labels inform users of specific risks associated with a product.
Adhering to the safety guidelines with respect to specific hazards can significantly reduce the risk of injury, fire, and in extreme cases even death. Not only should students learn to recognize the hazards associated with various safety symbols, but they should also be taught what actions should be taken to properly handle these chemicals and appropriate safety precautions.
Creating Laboratory Routines
Just like routines are essential for classroom management, they serve a similar purpose in the laboratory environment. If students know what to do at every step during their laboratory session it minimizes the likelihood of accidents occurring:
Considerations for a laboratory routine can include:
Protocols for what students should do before every lab session in terms of personal protection (see the section on What students need to know).
Preparations for lab work (e.g rereading instructions and MSDS sheets before commencing).
Whether or not students should sit or stand when conducting lab work, (they should stand, especially when heating substances).
Guidelines for storing bags and books.
Procedures for spills, accidents, or injuries (e.g report all accidents to the teacher and report and wipe up spills according to teacher’s instructions).
Safety in the Chemistry Lab
When conducting practical activities in the chemistry lab students will be exposed to a number of different chemicals and gases that may be corrosive, flammable or even toxic. The use of acids and alkalis can result in severe burns to skin and other soft tissue.
Rules and regulations vary from lab to lab but some safety protocols students should be taught when handling chemicals include:
Wear appropriate chemical-resistant gloves before handling chemicals.
Check the label to ensure the correct substance is being used.
Always use a spatula (or scoopula) to remove solid reagents from the reagent bottles. This should never be poured out of the container.
Hold containers always from your body when transferring chemicals from one container to another. Additionally, when chemicals are being poured from reagent bottles, they should be poured label side up.
Never heat flammable liquids over a direct flame. A water bath should be used.
Never add water to concentrated acids. Concentrated acids should be added to water slowly.
Never mix chemicals that are not called for in the laboratory instructions.
NEVER return excess/unused reagents to their original container. Dispose of the excess in the appropriate waste container.
Clean up all spills promptly as instructed by the teacher.
Resources for teaching lab safety
The lab safety Lesson pack is appropriate for younger students (ages 11-14). This resource includes lab safety contract, and other lab safety activities including role-playing activity lab safety dominoes for learning the safety symbols, a lab safety poster assignment (rubric included), and a few other activities.
The NC BioNetworks website also provides a virtual lab tour with a number of safety quizzes and interactive exercises that are useful for teaching lab safety remotely. Students receive a certificate after they have successfully completed the tour.
References:
Liability of Science educators for laboratory safety: National Science Teaching Association
Adopted by the NSTA Board of Directors, September 2007
National Science Teachers Association (NSTA). 2014a. Duty of Care.
Ryan, K. 2001. Science classroom safety and the law: A handbook for teachers. Batavia, IL: Flinn Scientific, Inc.
School Chemistry Laboratory Safety Guide
Department of Health and Human Services; Centers for Disease Control and Prevention National Institute for Occupational Safety and Health. “Https://Www.cdc.gov/Niosh/Docs/2007-107/Pdfs/2007-107.Pdf.”
U.S. Consumer Product Safety Commission, 2006.