The Science Teacher
September 2005, p. 24-29
Habits of Mind for the Science Laboratory
Lisa Hayes, Margaret Smith, and Charles Eick
Laboratory experiences should be an integral part of any high school science program, especially
laboratory activities designed so that students gather data, explore concepts, and answer questions
through inquiry (NRC 1996, p. 23). While conducting inquiry investigations, every science teacher must
properly instruct, supervise, and maintain equipment and materials to ensure student safety in the
laboratory. A number of cases exist in which students were inadvertently harmed due to a teacher’s
negligence in the laboratory (Figure 1).
Figure 1. Cases in the news.
“A Connecticut high school teacher substituted mercuric oxide for silver oxide in an experiment.
Twenty-two students working in pairs heated 1.75 g over a Bunsen burner for 15 minutes. After massing
the heated material the teacher realized that the mercury was being vaporized and the students were
evacuated. Three days after the incident, testing of the students revealed eight of them had elevated
mercury in their urine. Three months later one student still had elevated mercury levels” (CDC 1988).
“A student received minor facial injuries when she added concentrated sulfuric acid to a wet test tube
provided by her lab partner. The contents boiled out of the tube and struck her in the face. Her lab
partner had not dried the tube as instructed” (Young 2000).
“A 14-year-old boy put potassium dichromate in a bottle of soda two students were sharing in a physical
science lab. The two students became seriously ill and were rushed to a hospital” (Kingsley 1999).
“A 17-year-old…was electrocuted during a 1997 classroom science experiment in the 3,600-student
Franklin County, Ga., school district. The experiment involved stringing a wire around the classroom
and cutting away insulation at several points so students could attach probes from a voltmeter to learn
how to measure electricity” (Hoff 2003).
According to the Council of State Science Supervisors, negligence is defined as “conduct that falls
below a standard of care established by a law or profession to protect others from an unreasonable risk of
harm or the failure to exercise due care” (CSSS, p. 2). So, how can science teachers avoid negligence
and minimize the risk of accidents when preparing for, instructing, and supervising students before,
during, and after lab? Cultivating the following “habits of mind” at each stage of laboratory work is the
first big step toward achieving safety in the laboratory setting.
Habits of mind before the lab
Lab safety begins with the teacher. Teachers must make learning how to be safe an integral and
important part of their professional development and work. Teachers who are unfamiliar with laboratory
instruction should take whatever steps necessary to prepare for the unique challenges associated with
safety in conducting laboratory investigations and demonstrations. Attending workshops and
conferences, along with researching safe laboratory practices, can provide a foundation for
understanding and implementing safe laboratory guidelines and procedures.
Developing an atmosphere of “safety first” is perhaps the most important aspect of establishing the habit
of mind for lab safety. The following suggestions will help lay down the foundation for a safe laboratory
climate. The teacher should

instruct students using a clear set of laboratory safety rules, procedures, and penalties before ever
going to lab (Figure 2);

document evidence of instruction on safety guidelines through lesson plans, safety posters in lab,
student assessment, and parental/student signatures on easily read and understood safety
contracts (Figure 3); and

document student attendance for safety instruction, providing instruction at a later time for any
absent students.
Figure 2. Laboratory safety rules. (Adapted from the safety contract that Flinn Scientific publishes for
public use online at www.flinnsci.com.)
Introduction and purpose
Science offers “hands-on” laboratory experiences. You will be doing many lab activities that require the
use of chemicals and equipment that can potentially be hazardous. In this class, Safety is the #1
priority! To ensure a safe working environment for everyone, you must adhere to the following safety
guidelines at all times.
I. General guidelines
A. Follow all instructions carefully.
B. Never work alone in the lab.
C. Never touch equipment, chemicals, or other materials without permission.
D. No food, drinks, gum, or candy in the lab.
E. Perform only authorized experiments.
F. Be on your best behavior in lab—no horseplay, practical jokes, or pranks!
G. Keep your work area clean and tidy at all times.
H. Know the location of and how to use lab safety equipment.
I. Always be alert to potential hazards and work cautiously in the lab.
J. Dispose of chemicals according to the teacher’s directions. No solids in the sink! Put nothing in the
sink without consulting your teacher.
K. Read all labels carefully before using chemicals.
L. Keep your hands away from face, mouth, eyes, and body during experiments and wash them before
you leave the lab.
M. Clean, rinse, and dry all equipment and return it to its proper place.
N. Never leave your lab station unattended!
II. Clothing
A. Chemical splash goggles and aprons must be worn during all laboratory experiments.
B. Inform the teacher if you wear contacts.
C. Dress appropriately for lab—wear closed-toe shoes, tie hair back, remove rings and watches, and do
not wear loose clothing.
III. Accidents and injuries
A. Report ALL accidents to your teacher immediately—even the small ones!
B. Chemicals in the eye should be flushed with tepid water from the eyewash for 15—20 minutes.
C. Chemicals on the skin should be washed with soap and water, or in the case of a large-scale spill the
safety shower should be used.
IV. Handling chemicals
A. Consider all chemicals dangerous—do not touch, taste, or smell without specific instructions. Use the
wafting technique when testing for odor.
B. Check labels twice before using a chemical. Take only the amount you need.
C. Never return unused chemicals to their original container.
D. When using concentrated acids and bases, practice extreme caution. Add acid to water when diluting
concentrated acids.
E. Do not use flammable materials near open flames.
F. Be very careful when carrying chemicals around the room.
V. Handling glassware and equipment
A. Never handle broken glass with bare hands. Notify the teacher if you break something.
B. Broken glass is only disposed of in the broken glass container—never in the regular trash.
C. Be careful using electrical equipment—make sure plugs and cords are in good condition and that your
hands are dry.
D. Check glassware before use and report any chips or cracks.
E. Use the correct equipment for the task.
F. Use safety equipment when handling heated equipment and do not place hot glass directly on the lab
table or under cold water.
VI. Heating substances
A. Follow all instructions and safety precautions when using a gas burner.
B. Never leave a lit burner unattended.
C. Direct substances being heated away from yourself or anyone else.
D. Use insulating materials or tongs when handling heated equipment.
E. Do not place hot equipment on the lab table—use an insulating pad or wire gauze.
F. Do not place hot equipment on a balance—let it cool first!
Figure 3. Laboratory safety contract.
I, _________________________________, have read and agree to follow all of the safety rules set forth
in this contract. I realize that I must obey these rules to insure my own safety, and that of my fellow
students and instructors. I will cooperate to the fullest extent with my instructor and fellow students to
maintain a safe lab environment. I will also closely follow the oral and written instructions provided by
the instructor. I am aware that any violation of this safety contract that results in unsafe conduct in the
laboratory or misbehavior on my part may result in being removed from the laboratory, detention,
receiving a failing grade, referral to the office, and/or dismissal from future labs.
________________________________________
Student Signature
____________________
Date
Dear Parent/Guardian:
We feel that you should be informed regarding the school’s effort to create and maintain a safe science
classroom/laboratory environment. With the cooperation of the instructors, parents, and students, a
safety instruction program can eliminate, prevent, and correct possible hazards.
You should be aware of the safety instruction your son/daughter will receive before engaging in any
laboratory work. Please read the list of safety rules your child received. No student will be permitted to
perform laboratory activities unless this agreement is signed by both the parent/guardian and the student
and is on file with the teacher.
Your signature on this contract indicates that you have read the Safety Rules and Contract and are aware
of the measures taken to insure the safety of your son/daughter in the science laboratory, and will instruct
your son/daughter to uphold his/her agreement to follow these rules and procedures in the laboratory.
_______________________________________
Parent/Guardian Signature
____________________
Date
Science teachers must continually have safety on their minds before going to each and every lab.
Instructing students in proper lab safety is not a “one-shot” deal. Teachers must again document and
provide clear instructions regarding specific laboratory procedures and specific safety issues pertaining
to each lab activity. Teachers may wish to model certain equipment setups or techniques for students if a
portion of a lab activity is particularly difficult or requires observing a technique beforehand. Prelab
quizzes are also an effective tool to determine if students are prepared for a particular lab and have read
both the safety precautions and lab procedure (Figure 4).
Figure 4. Prelab quiz.
Chemistry prelab quiz Name ____________________________________
Hydrated crystals Block _________ Date ___________________
Guiding question: What is the formula of hydrated magnesium sulfate (Epsom salts)?
Background: Hydrates are compounds that incorporate water molecules in their crystalline structures.
The ratio of moles of water to one mole of the anhydrous compound is a small, whole number.
Answer the following questions—you may use examples to explain calculations.
1. What safety precautions must be observed when lighting and using a gas burner?
2. How will you experimentally obtain the mass of water and the mass of the anhydrous magnesium
sulfate in the hydrate?
3. How will you convert your experimental masses to moles?
4. How will you determine the formula for the hydrated form of the magnesium sulfate?
5. If, when you are heating your hydrated magnesium sulfate, your crucible cracks or falls off the ring
stand, what will you do?
Answer Key
1. What safety precautions must be observed when lighting and using a gas burner?
Long hair should be pulled back and loose clothing secured; do not wear dangling jewelry; make sure
no flammable materials are in the area; cotton clothing is preferred; do not leave lit burner unattended;
turn off gas as soon as you are through using the burner. Before lighting, be sure to know how to adjust
the burner’s flame and how to turn it off quickly.
2. How will you experimentally obtain the mass of water and the mass of the anhydrous magnesium
sulfate in the hydrate?
Determine the initial mass of the hydrated Epsom salts. After heating, determine the mass of the
anhydrous compound. The difference between the two masses is the amount of water driven off of the
hydrate.
3. How will you convert your experimental masses to moles?
Determine the molar mass of each compound. Use this to convert from mass (in grams) to moles.
4. How will you determine the formula for the hydrated form of the magnesium sulfate?
Divide the number of moles water by the number of moles of the anhydrous compound. This will give the
experimental number of moles of water relative to the magnesium sulfate.
5. If, when you are heating your hydrated magnesium sulfate, your crucible cracks or falls off the ring
stand, what will you do?
Immediately turn off the gas. Do not touch the crucible! Notify your teacher at once.
Habits of mind when considering a lab
Figure 5. A typical lab activity, then and now.
Guiding question: Can you experimentally identify the freezing point of a substance?
Traditional, less safe method: Graphing latent heat of fusion of naphthalene
Safety issues: Moderately toxic organic chemical and skin irritant; requires good ventilation in use; use
of Bunsen burner flame
Put naphthalene crystals in a test tube. Place a thermometer in the naphthalene. Heat gently with a
Bunsen burner until the naphthalene has melted. Stir the naphthalene gently with the thermometer while
it is cooling and record the temperature every 15 seconds for about 7 minutes. Plot a graph of
temperature versus time.
Alternative, safer method: Graphing latent heat of fusion of water
Safety issues: Safe chemicals (salt, water) and no Bunsen burner flame or heat
Place 5 mL of water into a test tube. Place a thermometer in the water. Place ice cubes, salt, and water
into a 400 mL beaker. Lower the test tube into the ice-water bath. Stir the water in the tube gently with
the thermometer while it is cooling and record the temperature every 15 seconds for about 15 minutes.
Plot the graph of temperature versus time. Note that you must continue to stir and maintain the ice-water
bath for the entire time.
Science teachers must have a strong understanding of the potential hazards of performing laboratory
procedures and the use of equipment or chemicals before conducting a lab with students. Many concepts
explored in lab can be done with considerably smaller amounts of chemicals (microscale), very dilute
solutions, or inherently safer materials. Science teachers should always ask themselves, “Can we teach
this concept another way in the lab?” or “Do the risks associated with this activity outweigh any
potential learning outcomes?” Teachers should consider the following points before choosing a lab
activity:

Only the most dilute solutions of acids or bases should be used and students should never be
allowed near stockroom concentrations of any chemical.

Hazardous chemicals or procedures that provide “shock and awe” should be avoided.

Chemicals or lab activities that are inherently safer than traditional approaches should be used
(Figure 5).

The chemical’s Material Safety Data Sheet (MSDS) should be consulted for each chemical’s
hazards (physical and toxological properties) to decide if it is appropriate to use (See
http://hazard.com/msds/ for all MSDS data sheets).

Disposal issues should be considered before deciding to perform a lab or demonstration. If the
waste product can’t be disposed of properly, the lab should not be done.

Teachers should consult their state’s banned list of chemicals that should never be used in high
school laboratories. Teachers can ask their state science coordinators for this list or use a safety
reference text such as Investigating Safely (Texley, Kwan, and Summers 2004).
When considering adding a new laboratory activity to the curriculum, teachers should consult
experienced science teachers who may have performed the same or a similar activity and who
themselves run a well-organized laboratory program. These teachers have the experience and expertise
to determine the safest approach possible in laboratory choices. An experienced teacher can also provide
guidance in terms of waste disposal at the completion of lab. Because most schools do not have the
luxury of a safety officer to arrange for removal of hazardous materials, activities that generate waste
that cannot be flushed down the sink, placed in a solid waste landfill, or otherwise be managed by the
individual teacher on site should be avoided. Teachers can ask for advice in substituting chemicals or
alternative methods of performing the activity that do not generate hazardous waste.
The most important point to remember before performing a demonstration or starting a lab is that
teachers must first do the activity themselves. Both safety and pedagogical reasons dictate the need for
practicing laboratory activities prior to their actual use in the classroom, especially those activities that
are new to staff. Practicing the lab helps teachers determine any potential safety hazards students may
encounter along the way. Also, practicing can help teachers clarify the procedure for students.
Habits of mind during lab
Laboratory experiences are ultimately used to introduce, teach, or apply scientific concepts through
process. Therefore, teachers have to use lab time for instruction and to help students make connections
between theory and application. However, teachers must also actively attend to their primary duty of
supervising students during the lab activities to monitor safety and behavior. In order to effectively carry
out both of these duties during lab, the following suggestions can help create a safer lab environment
where optimum learning can take place:

Eliminate procedural confusion beforehand by reviewing the lab, paying special attention to
safety issues, disposal, and cleanup. Use pictures or diagrams to show students how to set up
equipment.

Set up the laboratory to minimize student movement. Have students assigned to clearly marked
lab stations and have most, if not all, of the materials they need at their station. In inquiry-type
investigations, try to anticipate the materials students are likely to need, and make these available
at individual stations.

Provide chemicals needed at each lab station in small, labeled, unbreakable containers or dropper
bottles. Provide lab groups only the amount needed for the lab.

Provide a central location for materials that cannot be placed at individual stations and for
collecting waste at the conclusion of the lab.

Have a laboratory cart available with extra stock materials in the event a lab group does not have
sufficient chemicals to complete the lab and to quickly refill containers between classes. Extra
glassware should also be available in the event of breakage.

Review location and operation of engineering controls (e.g., master shutoffs) and safety
equipment (e.g., fire blanket, eyewash station, fire extinguishers).
Habits of mind after lab
A laboratory activity is not finished until all lab groups have completed the exercise, cleaned up their
work area and materials, and been checked out by the teacher. Teachers should stress the importance of
completing all of these steps as an integral part of the activity. Recommendations for maintaining safety
throughout this phase of lab include:

Review MSDS information with students and have location in lab for sheets when chemicals are
being used (this should be done before and after the lab).

Remind students of your expectations and procedures for cleaning up the lab and returning
materials that were discussed at the beginning the lab.

Be specific in telling students where to return borrowed materials and how to clean up equipment
(e.g., quick rinse, wash with soap, brush off balances).

Remind students to keep their chemical splash goggles, gloves, and apron on until they are ready
to leave the lab area. Even if a student is finished with the lab, there is still the potential for
chemical splashes and broken glassware during cleanup.

Check lab stations before dismissing students. Ensure that all equipment is properly cleaned and
stored and that there are no items missing from the lab station. Particularly hazardous tools such
as scissors or scalpels, if used, should be numbered and assigned individually, to be sure all are
returned at the end of the activity.

Remind students to wash their hands with soap and water before leaving.
Making cleanup part of a teacher's evaluation can be helpful in accomplishing the task to satisfaction.
There are numerous ways to accomplish this, from simply making a visual inspection of the lab station
and requesting that students correct errors to initialing a lab handout or lab notebook during the station
checks. Cleanup (and safety compliance in general) can also be included as part of the grade or grading
rubric. Student checklists for self-verification of completing cleanup procedures can also be provided.
Checklist for self-verification of completing cleanup procedures.
At the end of lab . . .

Shut off all faucets and gas lines, close fume hoods.

Dispose of chemicals as directed by your teacher. [Never put unused chemicals back into their
original container.]

Clean and dry all glassware, store as directed.

Clean equipment, but do not wash. Some laboratory equipment is sensitive to washing with water
and should be wiped but not watered down.

Return borrowed materials to their common table.

Clean and dry your lab table.

Store lab aprons appropriately.

Place chemical splash goggles into the appropriate container for cleaning.

Wash hands thoroughly with soap or detergent before leaving the lab.
Laboratory work is an integral part of teaching and learning science. Laboratory activities do not have to
be abandoned because of liability and safety concerns, but instead should be reexamined in light of the
habits of mind science teachers must practice to keep everyone safe. Examining one’s practice when
considering, instructing, supervising, and completing laboratory activities is the best insurance against
potential accidents.
Lisa Hayes (e-mail: lisa.hayes@opelikaschools.org) is a chemistry teacher at Opelika High School,
1700 LaFayette Parkway, Opelika, AL 36803; Margaret Smith (e-mail: smithmm@auburn.edu) is
Laboratory Safety Manager at Auburn University, Risk Management and Safety, Auburn, AL 36849; and
Charles Eick (e-mail: eickcha@auburn.edu) is associate professor of secondary science education at
Auburn University, 5040 Haley Center, Auburn, AL 36849.
References
Centers for Disease Control and Prevention (CDC). 1988. Mercury exposure in a high school
laboratory–Connecticut. Morbidity and Mortality Weekly Report. March 18.
Council of State Science Supervisors (CSSS). Science and safety: Making the connection.
http://csss.enc.org/media/scisafe.pdf.
Flinn Scientific Company. www.flinnsci.com/Sections/Safety/safety.asp.
Hoff, D.J. 2003. Science-lab safety upgraded after mishaps. Education Week. April 30.
Kingsley, W.K. 1999. Lock it up and throw away the key. Chemical Health and Safety. March/April.
National Research Council (NRC). 1996. National science education standards. Washington, DC:
National Academy Press.
Texley, J., T. Kwan, and J. Summers. 2004. Investigating safely: A guide for high school science
teachers. Arlington, VA: NSTA Press.
Young, J.A. 2000. Getting students to wear safety goggles. Journal of Chemical Education 77(9): 1214.