Lab Prep Tips

Amy Snyder | Thu, 05/11/2023 - 15:13

As we approach Graduation season, I’ve been considering all the new teachers we will have joining our schools in the very near future, and thinking back to my first year as a Biology and Chemistry teacher in 1997. There are many skills and techniques that may not be formally taught to preservice teachers, no matter if they go through alternative certification (a growing trend) or a prescribed University Education curriculum. The first that comes to mind is classroom management, and specifically as a science teacher, managing labs. Knowing how to set them up, facilitate them and clean them up was definitely one of my earlier weaknesses- even though I student taught in Chemistry and Biology secondary classes and had a fantastic experience under John Penick and Bob Yager at the University of Iowa's Science Education program.

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I learned by doing and lots of mistakes were made. I remember my worst lab setup (even though I can't remember the actual skill or topic it was about) where I set up a central location for all the consumable chemicals, thinking it was most economical. One problem with this - students had to wait in line. They contaminated chemicals by using one scoop for everything even though each beaker had its own. They spilled chemicals everywhere, forgot to tare their weighboats, and didn't have enough time to actually perform the experiment and gather data. In their haste to get out of the room they left me with several beakers (too full to be economical) of contaminated substances, a huge mess to clean up, and lots of glassware everywhere. I'm sure we’ve all had one of those days at the start of our careers. Just me? Cool, cool.

Teacher Tips:

Over the years I've learned some tricks and other well respected teachers (aka my Twitterverse PLC of #iteachchem) have some also, so thought I'd share those here.

Scott Milam, @IBchemJedi, suggests using Pivot labs (a remarkable interactive website) to cut down on set up, and I’ve used them as pre-lab activities as well to double check the students’ understanding of what is happening and what they should expect to see in the lab. It has reduced the number of contaminations, errors, and student confusion.
I have asked students to read the lab the night before, and created a quick formative assessment with a microsoft or google form with 1-2 questions or calculations for them to complete when they enter the room. This way I can see who really needs help before they begin, and finish up any last minute set up or restocking while they work on them.
Always do the lab first yourself to make sure the procedure is clear and reasonable data can be acquired with your specific equipment and materials. Try to think as an inexperienced teenager, and don’t let the Curse of Knowledge interfere. Phillip Cook (@chemteacherphil) supports this idea: “Focus on understanding the experiment from the perspective of likely student procedural mistakes and above all, how to communicate safety precautions related to the lab.”
Kristen Drury (@APchemisMe) records a video of herself offering “tool talk”: explaining how to use the equipment as a pre-class tutorial so they don’t need to use class time.
Always include safety precautions in the written instructions as well as the verbal. None of us can afford any injuries or slip ups, and this is an extra layer of responsibility for us as science educators. The American Chemical Society has created a quick read booklet, Guidelines for Chemical Laboratory Safety in Secondary Schools, and the CDC offers the School Chemistry Laboratory Safety Guide. On a side note, I've always thought we should have an additional insurance rider provided by our employers or unions for this, specifically.
Danny Wilks (@dwilkssea) wisely advises: “Budget more time for setup the first year than you think you need.”
Try for microscale versions if at all possible. Green chemistry is the design of chemical products and processes that reduce or eliminate the generation of hazardous substances. The EPA has identified 12 principles for green chemistry here.

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screenshot of interactive 12 principles of green chemistry from Beyond Benign

Visit Beyond Benign for an interactive version of this image and many other resources!

DO NOT stay in one place in the lab! For safety, chemistry teachers must constantly be present and have their head on a swivel. This is also a fantastic chance for a formative assessment! Have a small list of questions available to ask each lab group to keep them engaged and make sure they are progressing and focused on the task at hand. Consider questions like, “How are you recording your data? What would happen to your results if I happened to spill this reagent right now? Why did you pour that into the beaker when you did? Would it make a difference if you stirred that solution, or should you leave it alone?” Point out how great some groups are working or exemplary results (especially gratifying with chromatography, titrations, and selective precipitation) to the class during natural breaks in the activity. These questions will come to you more naturally if you do the lab yourself and find the pitfalls. But there are also these cool cards by paul anderson on wonderofscience.com that have some good non specific questions that could be asked during lessons and labs - supported by NGSS, of course.

Label everything! Solutions with your initials, molarity, date prepared. Beakers with name and formula of substance within, trash beakers for specialized disposal. Label the “acid” and “base” burette for a double titration. Label the pipettes (glass or transfer), scoopulas, test tubes and/or beakers being used for each substance to prevent cross-contamination, even if you do trust the kids to get it right. Early on (and depending on the level of the course) I've even labeled “Erlenmeyer flask” and “volumetric flask” to help identify proper glassware. I’ve also used a sharpie to label weigh boats with specific substances to eliminate contamination with early Chemistry learners.

The next few suggestions may pertain to the time of the school year and how much you choose to challenge the students:

To save time, hook up and test your bunsen burners, burets, vacuum filtration, and any digital sensors. Calibrate pH sensors and check the storage solution levels. As the year/mastery level progresses, these are skills the students can accumulate themselves.
Place glassware on one side of the room and consumables on the other so the lab group must split up and delegate set up tasks.
Create 'kits' of standard lab equipment that stay on the lab tables or in lab drawers that the students are responsible for keeping clean and unbroken. I keep scoopulas, cuvettes, sparkers, test tube brushes, a thermometer, stir rod, a couple watch glasses and well plates, universal pH strips, a baggie of standard size filter paper, and various tongs & clamps in a clear plastic shoebox at each station numbered or color coded to match each lab table. Every year I’m surprised with the curiosity of learners using some of these tools in novel ways. I also like assigning a balance, burner, and buret to each station so measurements and results are precise from class to class and day to day.
Create a kit for each lab that contains unique glassware (i.e. Buchner funnels, alcohol burners, eudiometers and such) and materials for each lab. Once you complete the lab, refill sealed containers with consumable substances for the next year, along with any reflections or notes about how you set it up in the room, particular successes, sample data, good pre-lab questions, and common student misconceptions to preview before performing the lab.
Have the last class of the day return the equipment and materials to specific locations. I like to have a cart for glassware where the top shelf is dedicated to Erlenmeyers, middle shelf for beakers, bottom shelf for Volumetrics. I have another cart for substances. Students have to group all the calcium carbonate containers together on one shelf, then sodium chloride in another row, for example. This organization makes putting things away and doing dishes easier, and reinforces their vocabulary. These procedures also make it easy to see if anything had broken or immediately needs replacement in case I need to continue the lab the next day. If you need to bounce or travel between preps within one day this would also be helpful to do at the end of each class.
Personally, I try to stay away from station labs where a small group of students follow each other around and do a short experience, like mixing two substances out of droppers, before moving on to another station. I have found that if one group doesn’t clean up after themselves, the others just look at what was already done without actually experiencing it themselves. Often, one group can't complete the task in the predetermined time allotment, and the whole train gets backed up. I definitely see the benefit of moving them around the room, and quick experiences. So I prefer to set up a series of stations around each lab table so each group has only one table to move around, or two to three sets of stations in the room so more action can happen simultaneously.

Twitter Tips:

In February 2023, I got some marvelous responses to my tweet:

“#iteachchem folx- if you were to help #preserviceteachers learn how to set up labs, what would you share w/ them? @ChemEdX @ChemEdXpert”

KVanderveen (@kristenvdveen) had these fantastic ideas:

Sometimes color coding labels if there are multiple steps. - Buy prepared solutions to save time. - Prepare enough materials (in the bin for that lab) so that you have enough to run the lab for several years.

Michael Weir (@Weirdchem) responded with:

Have students do some of the setup and cleanup work. Think stations and groups so you can adjust to different class sizes. Small sealed containers of reagents with backups pre-made. Color and phase changes for interest.

Ethan (@scienergetic) says:

1) Microscale when possible.

2) Bins or small containers for portability and ease of setup. Color-coded and/or numbered or lettered.

3) When possible, minimize congestion & motion: have 14 students do the lab while the other 14 work on something else, then switch.

Daniel F. Smith (@TungstenW) advises:

Try to use the smallest amount of reagents with the fewest number of containers to complete the lab.” (I like his note about containers - I don’t know anyone who likes washing glassware!)

Dr Michelle Herridge (@mdhh99) suggests educators should know:

1. Where to find good resources/references to explain the science.

2. Safe storage and which chemicals have the most versatile uses (variety of labs).

3. Public speaking and showmanship (how to create interest and surprise).

Hannah Nandor (@nandorscience) supports the label everything idea:

Rotating stations involve more movement but can help with student time management and material prep. Lunch trays help keep things contained on lab benches. Label EVERYTHING.

MrBChemNHS (@ChemNHS) has these tips to save time for all of us:

1.) Triple check your procedures before giving them students.

2.) Find some resources that have good ideas so you don't have to reinvent the wheel every time, but tweak them for what you have.

I hope these suggestions have given you, a mentor, or mentee some ideas to streamline lab activities moving forward! Please don’t hesitate to reach out with any clarifying questions or additional suggestions!