5 Safety Tips for Chemical Demonstrations
and Hands-on Activities for K-8 By Valerie Coskrey
I once attended a workshop designed
to show teachers how to use science demonstrations to motivate children
to learn science. An exciting demonstration suggested for teachers of
grades 4-6 was colorful and showed rapid expansion of a foamy substance.
Looked like the makings of a fiery volcano.
During the discussion of the demo, it became apparent to me that only
an elementary school teacher with some chemistry background would be
able to do the demonstration. The chemicals used were strong acids,
the safety precautions needed were elaborate, and the potential for accident
was high. In the hands of a knowledgeable teacher, the demo would have
been appropriate; otherwise, the liability would have been unacceptable.
Would the training of one workshop have been adequate? Maybe. Maybe implementing
the suggestions below will be sufficient for most demonstrations. But
I would not recommend that a teacher without some science safety training
do the above demo in a classroom with children.
What are the safety measures that are necessary
for such demos? Let
me suggest some of the safety measures that can be used with chemistry
demonstrations and activities in elementary school science.
- Have an accident clean-up kit positioned within easy reach of the
teacher.
- Work on a chemically inert surface that is
large enough to place the materials and do the demonstration without
the demonstrator feeling crowded or awkward.
- Dress yourself and all students that are participating in the demonstration
or hands-on activity in chemical splash goggles
and plastic or rubber-coated aprons; also, closed-toed shoes and
tied-back long hair are a must. Have all other students keep far enough
back that no splashes or spills will make contact
with the student.
- Purchase and store only enough chemicals for your immediate needs.
Be sure all chemicals are properly labeled and
stored in a locked cabinet.
- Do all demonstrations and hands-on activities at least once in the
company of another adult before showing/doing the lab with the children.
Discuss and arrange for any safety precautions that become evident
from your trial run, from your reading about the activity, and from
your knowledge of science activity safety precautions
and rules.
When do these rules not apply? When the chemicals you are using are
only baking soda, vinegar, common table salt, soap, sugar, toothpaste,
litmus paper, lemon juice, common metal strips, chalk,
charcoal, food coloring, most foods (except raw meat), ice and cold
water. For any other chemicals, I suggest using the rules above strictly.
For this short list of chemicals, I recommend using the rules to model
safe practices. And the soap is ok only if no one gets soap in his/her
eyes. If the water is heated, goggles and aprons are mandatory.
I know. This set of rules seem to take the fun out of science. But safety
must come first. Try using colored goggles that fit well and inexpensive
plastic aprons aprons that students can autograph with marking pens.
Hang safety posters on the walls and discuss safety rules with students
before they do the activities. Discuss safety before and after a demonstration.
Let students brainstorm safety needs.
Is this an exhaustive list? NO. This is just an introduction to the
topic of safe procedures in science activities. It is the basic requirements
for any science activity that uses chemicals other than those that are
inert or only weakly reactive.
What is an accident clean-up
kit? Spills happen. Most chemical activities involve
at least one acid or base. Glass breaks. Fires are needed to heat
substances. Having some items at hand to take care of any potential
problems is necessary.
In my non-lab classrooms, I found these supplies allowed me to do chemical
activities safely.
- Spills can be contained using sand or kitty
litter. Keep a bucket
of the stuff handy--with a scoop--to toss onto a spill.. Use a broom
or brush and a dustpan to sweep up the mess that is now much drier.
Dispose in a plastic plastic bag stuck into an old coffee tin or
oatmeal box--or larger heavy plastic paint can, whatever you have.
Be sure the container will not react with the chemical spilled. Then
use a copious amount of water to rinse the surface of the floor or
table. Use litmus paper to check if the surface is acidic or basic.
If so, neutralize.
If the chemical is organic, use soap. Most inorganic chemicals will
rinse away--but you have to know if they will react with metal plumbing,
create poisonous gases, or irritate the skin. So soak up the rinse
water with a sponge and rinse several times.
- ...
- Keep baking soda around to use a a quick buffer for neutralizing
acids and bases that spill or splash on someone. I buy it by the pound
box at the grocery store and keep it in old parmesan cheese plastic
jars with the sprinkle tops. It will buffer acids in the dust left
after the sand or kitty litter is swept up. A bit poured on the spill
before the sand or kitty litter is poured helps, too. It will wipe
up when you rinse with your sponge and cold water. If the spill is
basic, then the baking soda will fizz until the base is neutralized.
Keep a plastic bottle of vinegar to further clean up after a base spill.
Rinse well. Since elementary school activities should use only weak
concentrations of acids and bases, these measures should suffice. If
stronger acids or bases are used, such as lye (Draino) or bleach (actually
a salt, but treat as an acid) or muriatic acid (hydrochloric acid),
prepare diluted solutions in advance when the children are not present.
If strong solutions are needed, pour out small quantities into
a small capped container and use this in the activity. Keep the larger
stock bottle locked away from the children. Use eye droppers (dropping
pipets) to transfer liquids drop by drop, or pour carefully. Always
add to water. Never put an acid or base into a container
and then add the water. The mix will splatter. To be sure that the
chemical doesn't eat through the container, purchase bottles. caps,
test tubes, and beakers from science supply or school supply sources.
Nalgene plastics and pyrex or kymex glass make safer container for
chemicals.
- ..
- Keep bottles of water on the prep/demo table. If
you do not have a sink within 2 feet of the activity, use 2 liter drink
bottles or gallon milk jugs to distribute water around the area. This
can be used to rinse up a spill. Most importantly, it can be used to
immediately rinse the skin of anyone that is splashed. Keep a bottle
of sterile water (unopened bottled water or distilled water) close
to hand to immediately rinse an eye that gets splashed. To catch the
water, I used shallow, rimmed plastic trays or teflon-coated metal
baking dishes to carry supplies to student stations/desks and then
told students to pour over the trays if water (or other liquid) was
used. Of course, for a rinse of skin or eye, a mess didn't matter.
Hide a few extras at your desk for replacement and refills. Water spills,
too. Be sure to tell the students that the bottles are not clean
enough to drink from, just rinsed out. They do get thirsty.
- ..
- Have a fire extinguisher nearby if you do anything
at all with flames: candles, alcohol burners, matches, whatever.This
is required. If the fire extinguisher for your classroom is down the
hall, make arrangements with a student to hang near the door and go
for it if necessary; make arrrangement with your principal to provide
one that you can carry into your room for the time of the activity;
inform all of the teachers that share the extinguisher that you will
have it in your room for the activity; or purchase a small one just
for your room for your convenience for several activities. You will
have alternatives to a fire extinguisher. Another use of the sand is
to throw it on a small flame. Just like at home, baking soda can be
used as in a small kitchen fire. And don't forget the water in the
bottles, but do not use on electrical, oily, or certain chemical fires.
Even so, have easy access to the fire extinguisher. Discuss with students
that if a fire starts and you do not immediately put it out, they are
to evacuate the room, walk calmly outside and gather at the fire drill
area, with one student telling the teacher next door to get help on
his way out.
- ..
- Pick up broken glass with dampened old newspapers or
paper towels. The damp paper should collect all the little grass splinters.Wrap
the glass pieces and damp paper in old newspapers and place the bundle
into a trash bag. This keeps the shards from tearing through the trash
bag and cutting anyone that removes the trash. Another technique is
to keep a broken glass box. Label it and keep it where the students
cannot get into it. Toss broken shards into it. When you get ready
to dispose of the glass, wrap it in newspaper or use the container's
lid.
What is a chemically inert surface?
You cannot do chemistry activities on top of paper
or cardboard like you can with art activities. You cannot do chemistry
activities on a desk covered with papers and books. Use a table covered
with melamine or some kitchen-like counter top. If you use a wood
surface, purchase the paint for chemical lab desks from a science
supply resource and paint the surface. Or use trays like those mentioned
above. Drop a bit of chemical on the surface of a tray you plan to
use. If it reacts with the surface, you know that a spill will be
dangerous. Use another surface for your activity. Try a teflon-coated
tray, a ceramic tile, or an enamaled metal panel from the side of
an old appliance or old broiler pan.
What are chemical splash goggles and
plastic or rubber aprons? These items are sold by school
and science supply houses. Sometimes you can get them at hardware
stores. The important thing is to look for the OSHA
Approved label.
The goggles for shop are not the same as chemical splash goggles.
Flimsy aprons will not protect from chemical splashes. Any child
not wearing this safety gear must watch the activity from a safe
distance. This safety gear is also necessary for children boiling
water in a science class. Some school districts might prefer face
shields to goggles, but one of them must be worn. Goggles come in
small sizes and bright colors now.
What is a properly-labeled chemical
container? It is usually better to store a chemical
in the original container. That way you have its name and safety
information that is on the bottle. Use a marker to put the date of
purchase on the container. It also helps to know
the date the container was first opened. If you mix a solution or
other mixture, or transfer a small amount to a bottle for use in
the activity, you must label the new bottle. Tape a paper label on
the container. If there is no room for the needed information, or
you want the chemical to be an unknown, use a number or letter matched
to another paper or card with the proper information. Include the
following information on your label:
- name of chemical(s) and solvent if dissolved in anything.
- date prepared
- who prepared it
- concentration
- original amount, marked or measured
- safety information or reference to such information
- comments
What are all the safety rules? For
more about safe practices, check with NSTA.
Flinn Scientific puts
safety information for teachers online and in their catalog. High school
science textbooks have safety information and basic rules lists. The
written rules often require a bit of interpretation, so read information
from several sources. Finally, make friends with a high school chemistry
teacher, and network.
As a high school chemistry and bioilogy
teacher and a college biology instructor, I have had to concentrate on
safe practices for teaching science. My association with elementary school
teachers and my experiences with small children have caused me to think
about what safety during an elementary school science lesson and preparation
would entail. Also, of course, I have been trained in school science lab
safety. |
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