Although I use ordinary substances such as baking soda, salt, sugar, lemon juice, and food coloring to introduce my third graders to simple chemistry concepts, no matter how often I remind them not to touch anything unfamiliar they inevitably do so. Much to my surprise, one day a hands-on chemistry investigation provided the inspiration for an effective safety lesson.

It all began simply enough when I asked children to put aside their art projects because it was time for science. To a room full of third graders and construction-paper art projects, I added water. What was I thinking? The children spilled liquid everywhere, and within minutes the dye from the construction paper had made their faces and hands red. That’s when it hit me that if the red solution had been a caustic chemical, there would have been serious injuries in my room.

The following week my lesson plans were to introduce acids and bases to my students. I came up with a plan to incorporate a safety lesson into the unit, and when I introduced the use of pH indicator paper as an acid–base indicator, I was all set with this hands-on investigation to introduce chemistry lab safety.

Exploring pH

I began the lesson by demonstrating the use of pH indicator paper to show that ordinary household (white) vinegar was an acid. With the students, I wondered aloud whether diluting the vinegar would make it less acidic. I divided the students into teams to explore our scientific question. Because not all the properties of vinegar are known by the students, they should wear eye protection and gloves, and a Material Safety Data Sheet should always be available. Download the MSDS for vinegar by clicking here.

Explore the topic of Chemical handling and safety

As the children began their dilutions, I went through the motions of looking for pH indicator paper and made a big show of discovering that my supply had disappeared. I asked the class whether there might be something else in the room that we could use. The children were eager to help. Some suggested that we might be able to reuse our old pH indicator paper, if we blotted it dry and bleached out the color that the vinegar had produced. I just “happened” to have a solution of dilute household bleach in my supply cabinet. (An MSDS for household bleach is available here.)

Wearing safety goggles, apron, and gloves, I followed the suggestions that the students had made. I bleached out the strip, dried it with a hair dryer, and tried to reuse it. Of course, the students’ plan could not work. (The indicator in pH paper is a pigment which is destroyed by bleach.)

The Teachable Moment

Next, students suggested that they might make their own pH indicator paper from the red construction paper from their art project if it were cut in strips. (They likely suggested this because they had seen red litmus paper.) If students are aware of the proper safety procedures for handling substances whose properties are not completely known or that are known to have dangerous or unpleasant effects, this sort of open inquiry should be encouraged. When working with vinegar in a science investigation in class, goggles and gloves are needed. I did nothing to discourage the children from testing their bits of paper. Of course, the dye from the paper got on their gloved hands and on other areas of the classroom. This provided the “teachable moment” for a lesson on science safety.

I called students’ attention to the way that the dye from the construction paper had spread around the room. They could see it on their gloves, on papers, and even occasionally on their skin. I went on to explain that if our experiment had involved a poisonous or caustic substance, there might have been a serious injury to someone. I also had the children look at the tinted vinegar-water mixture in their cups and explained that their test strips had contaminated the solution, something that could ruin a chemical experiment.

This was an ideal opportunity to remind students that it is important to immediately report any spill of an unknown substance. As a class, we made a list of ways that we could insure safety when unknowns or potentially harmful substances were used. The list included never touching unknown substances with your hands because they could sting or cause serious burns. Some of the students’ suggestions included wearing protective gloves and goggles, reading labels for safety information, holding the test strips down so that liquids could not drip on hands or arms, and holding strips with tweezers.

I also made a point to show the children what they should do if they accidentally got an unknown substance on their hands or faces. We talked about the use of an eyewash and how to safely clean up after chemical experiments. Some substances (like vinegar) can be washed down the sink with lots of cold water. Other substances that we use at home (such as oil-based paints) require special disposal. Your local municipality can tell you whether there are special places or dates for disposal of these substances and the location of hazardous waste disposal sites in your area.

Never Too Early—Or Safe

Later, I arranged for a representative of the fire department to visit our class to talk about chemical wastes and had the children make “Chemical Safety” posters to illustrate the safe handling of chemicals. In many areas, the fire department requests copies of a school’s chemical inventory so that they can be prepared for any accident.

Needless to say, this safety lesson is now the first activity I use whenever I introduce a chemistry unit. My students’ safety posters are used to make a bulletin board as a constant safety reminder. And now that I know how to teach children how to handle unknowns in a science classroom safely, I feel more comfortable about using these substances in my classroom and my chemistry unit has expanded.

This experience taught me that it is never too early to introduce young children to chemistry lab safety concepts like never tasting or touching unknown substances, no matter how harmless they may seem to be. As the “Chemical Safety Song” (Figure 1) reminds us, Safety’s First, Always First.

Judith Longfield (jlongfie@indiana.edu) is an assistant professor at Indiana University Northwest in Gary, Indiana. Special thanks are extended to high school chemistry teacher J. Scott Townsend, chemistry professor Linda Wozniewski, and chemical engineer Dana Dodson for help with the chemistry and chemistry safety issues in this article. Thanks also to Dorothy Gabel and Valerie Akerson for their assistance with early drafts of this article.

Resources

Bramdolini, A. 2003. Fizz, bubbles, and flash: Element explorations and atom adventures for hands-on science fun! Charlotte, VT: Williamson.
National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academy Press.
Sarquis, J.L., M. Sarquis, and J.P. Williams. 1995. Teaching chemistry with TOYS: Activities for grades K–9. Middleton, OH: Terrific Science Press.
Snyder, H. 2002. The extraordinary chemistry of ordinary things. New York: John Wiley and Sons.
VanCleave, J. 1989. Chemistry for every kid: 101 easy experiments that really work. New York: John Wiley and Sons.