As I reflect back on remote and hybrid learning during the pandemic, I recall my frustration as I made new lesson plans and reimagined lab experiments as at-home or virtual labs. I had expected that these would be short-term solutions that would probably never be used again — and also assumed that they would be less effective than in-person lessons. However, after returning to in-person learning, I now realize that these alternative lab approaches have unexpectedly turned out to be a bright spot for longer-term curriculum development in my classroom.

I have retained some of these alternative approaches to supplement my traditional, in-class chemistry labs. I will discuss these methods, some of which I developed collaboratively with my co-teacher, Laurie Smith. I regard these approaches not as replacements for in-class labs, but rather as opportunities for additional lab experiences. I generally plan one in-class lab experiment for each unit, in addition to the at-home and virtual labs, which means I’ve approximately doubled the number of lab experiences that my students have, compared to in-class labs only.

Students frequently note that labs are their favorite part of chemistry class and, in addition to being engaging, the labs promote useful skills in data analysis and enable students to actually experience science. I conducted these activities with my honors-level high school chemistry classes, but they could be implemented in regular-level or middle school courses as well.

At-home labs

Figure 1. Excerpt of class safety contract document.

At-home labs facilitate making connections to students’ daily lives, as they investigate with items in their kitchens. These activities provide additional hands-on experiences for the students, without using class time, and promote family involvement. My students have mentioned that their family members have been intrigued by what they are doing, and many enjoy the at-home labs more than the typical homework assignments.

These lab activities use safe, readily available household items, and are specifically outlined in the at-home section of our class safety contract (Figure 1). When needed, we provide students with some less common materials required for an experiment, such as pH strips.

We instruct students to let us know if other materials are needed, which we can provide. Alternately, we can arrange for the students to complete the lab at school.

Students submit a photo of their set-up, sometimes with labels, as part of their write-up. The photos help to ensure that the students are doing the activities themselves, and not just using the internet to find expected results.

Figure 2. Density column created in an at-home lab. Photo credit: Pippa Davison.

Figure 3. Marshmallows used in an at-home lab. Photo credit: Caroline Piccolo

The first at-home lab involves constructing a density column.¹ Students select three or four household liquids, such as water, dish soap, vegetable oil, or honey, and layer them according to their density (Figure 2). We provide them with plastic vials, but they could also use a clear drinking glass as an alternative. The visual result helps to reinforce the concept of density. The students submit a photo of their density column, labelled with the density, including units, of each layer.

When we learn about waves and the electromagnetic spectrum, students conduct an experiment to determine the speed of light using a microwave oven.² They remove the spinning plate and heat an easily-melted food, such as chocolate, cheese, or marshmallows (Figure 3).

The food will melt in concentrated spots at the crests and troughs of the microwaves, so the distance between these spots is half of the wavelength of the microwaves. The frequency of the microwaves can be read on the label on the microwave oven, and then the speed of light can be calculated. I love how this activity drives home the point that the microwaves that are cooking food in our ovens are actually part of the electromagnetic spectrum.

When possible, I aim to provide choices for the students, which gives them an opportunity to follow their interests and to take more ownership of their work. In this context, choice can also help address any potential issues with supplies, because students can choose an activity for which they have the materials.

For example, I offer my students a choice of four activities in the surface tension at-home lab, inspired by a PhysicsGirl video. These activities explore the surface tension of water in different ways, such as by floating a paper clip on water or counting the number of drops of water a penny will hold. They can observe the disrupting effect that soap has on the surface tension, by adding soap to the water with the paper clip or behind a folded card “boat” floating on water. The paper clip will sink and the “boat” will move forward.

Another option is to create “milk fireworks” by placing drops of food coloring on the surface of milk. Adding a drop of soap causes the dye to spread out rapidly as the surface tension of the milk weakens (this option is similar to the AACT activity, Colorful Milk). The surface tension activities bring a “wow” factor to the experience, and my students are impressed by the high surface tension of water that they observe.

Students also have a choice of materials in an activity where they test the pH of different household items. Using pH strips provided to them at school, they test beverages and cleaners, plus additional items from two categories of their choosing.

At-home inspiration from AACT

AACT provides many resources for at-home labs. You can find many great ideas in the Kitchen Chemistry Collection, which highlights the teaching resources found in the AACT library that only require materials typically found in the kitchen.

I also incorporate the lab, Chemistry of Hand Sanitizer and Soap, into my unit on intermolecular forces. This is a simple lab experiment where students use pepper flakes to represent virus particles, and then model the interactions with both soap and hand sanitizer. The accompanying ChemMatters article, What is Hand Sanitizer, and Does it Keep Your Hands Germ-Free? makes great connections among our class topic of intermolecular forces, real-world applications, and current events regarding virus protection.

Another point of inspiration from AACT is the “Burning Questions” at-home lab segment, from the AACT Virtual Summer Symposium: At-Home Activities and Resources for Teaching Chemistry Online. Students make close observations of a candle before, during, and after its burning. I chose this lab not only because of its connection to chemical reactions, but also its focus on the skill of observation, particularly of something very familiar to students. Of course, a burning candle is something that we have all seen many times before, but it is amazing how much more you can notice about it, if you only look closely! We also adapted the lab to include the ChemMatters article, Shining a Light on Candles (along with the graphic organizer from the Teacher’s Guide) to provide a chemical background on what the students are observing.

In addition, I added a second part to the segment where, similarly to the surface tension lab, students select from one of several options to explore combustion and how it can be extinguished.³ They can extinguish the candle by using carbon dioxide (either from their exhaled breath or from vinegar and baking soda), or by depriving it of oxygen by covering the candle with various-sized jars.

Since this lab involves flames, I carefully instruct my students on all the relevant safety warnings, and remind them that they absolutely must:

• ensure that no flammable materials are nearby
• use a non-flammable surface such as aluminum foil
• tie back long hair and loose clothing
• check in with parents or caregivers before starting, and
• never leave their burning candle unattended.

I assign this lab during our unit on chemical reactions, when we learn about combustion.

Virtual labs

Figure 4. Screenshot of a virtual lab offered by Pivot for students to investigate rate of reactions.

My school has purchased a subscription to Pivot Interactives,⁴ a platform that offers virtual chemistry labs. In contrast to computer-animated simulations, Pivot activities center around actual video footage of experiments and reactions. Students can pause the videos or move to any point in the video to collect data, aided by measurement tools, such as rulers and stopwatches, that can be overlaid on the video (Figure 4). Different videos can be selected based on such variables as various concentrations or reactants.

I see several benefits of supplementing my teaching with virtual labs, including:

• students can run more trials, analyze clearer results, and worry less about safety precautions regarding chemicals that would be hazardous if used in a physical lab setting
• these labs require less time, both for the students in terms of conducting the lab, and for the teacher in terms of setting up and cleaning up the lab, and
• they do not require any materials beyond an internet-connected device.

In addition, virtual labs can sometimes allow students to observe phenomena on scales not easily seen in person (in terms of time or size). For example, the precipitation reactions lab offered by Pivot features incredible close-up videos of the reactions that show more detail than can be observed in person.

All these benefits are considerable, yet they cannot replace the valuable, fundamental lab skills learned through hands-on opportunities in the chemistry laboratory. Virtual labs can support in-person labs, and achieving a balance between these various teaching methods is key to developing students’ lab and data analysis skills.

Using technology for pre- and post-lab support

I like to use virtual labs to support in-person labs, as either pre- or post-lab assignments. As pre-labs, the assignments can show students how the equipment is set up, or introduce them to the calculations that will be involved. For example, before doing a hydrate lab in-person, students do the first part of the appropriate lab on Pivot. They can see the set-up, and even try out the calculations using data from the video. As a result, they can be prepared for both the technique and calculations when they do it themselves in school.

Meanwhile, in the post-lab on Pivot, students can explore unexpected results and evaluate possible sources of error. Post-lab assignments can also include an application of what they learned in their in-person lab. For example, the students do a lab in school to develop an activity series. Then, for their post-lab on Pivot, they make predictions about various chemical reactions (pennies reacting to acid for example), and later view the videos to check their understanding.

Other technology tools, such as simulations and videos, can also be used to support in-person labs. For example, before doing a titration lab, I assign students to watch a video made by Carolina Biological showing the titration technique, and also answer some questions on the equipment and vocabulary. Another tool I’ve used is the simulation, Metals in Aqueous Solutions (developed by AACT), which can be used in conjunction with an activity series lab. The molecular scale view can help students connect what they observed in the lab with what happened on an atomic level.

Online tools can also develop students’ general lab skills. For example, the Graphing simulation by AACT introduces students to key components such as intervals and label, to include on graphs and gives them a practice quiz, while the Measuring Volume simulation includes a quiz that lets students practice recording volumes using the correct number of significant figures, accurately reading the meniscus, and determining uncertainty values. Meanwhile the simulation, Preparing Solutions quizzes students on molarity calculations, and also recaps the physical steps in preparing a solution of a given molarity.

New ways for students to make up labs missed due to absences

Figure 5. Screenshot from a lab video created by the author.

When students are absent on lab days, it can be quite difficult to arrange for them to actually conduct the lab as a make-up. Typically, there is a class scheduled in the chemistry lab every period, and after school is a challenge due to sports, clubs, and faculty meetings. Additionally, the lab area needs to be cleaned up after the scheduled day, and there may not be enough of the solutions remaining to re-run it for individual students. As a result, when students missed labs in past years, I often had to give them sample data to use to answer the lab questions, which meant that they did not experience how the lab was actually conducted.

Now, however, I can use an alternative lab approach to give these students a better, more engaging experience. One option I use for students who need to make up a lab due to an absence is to conduct a similar lab on Pivot, during which they can collect the data themselves and observe the results.

I also began creating my own inventory of lab and demo videos during hybrid learning. By filming myself doing the lab work or demo, I originally intended to create a resource for students learning at home.

I’ve found, however, that I can share these videos with students who are absent for a particular lab experiment or demonstration, so that they can see how it was done (Figure 5). The students record observations directly from the video, enabling them to see the same set-up their classmates used, and also to be more engaged in collecting the data. Although it takes some time to film and edit the lab videos, they can be used again in future years — and do not require a subscription.

Conclusion

At-home lab activities and virtual labs are useful ways to supplement and support in-class labs, each in its own way:

• At-home labs enable additional lab experiences and demonstrate the chemistry in everyday products and phenomena. They provide a more meaningful (and fun) assignment than traditional homework.
• Virtual labs facilitate experiments that would be difficult to do in-person, in terms of scale or materials, and also support in-person labs as pre- or post-lab assignments. Virtual labs and video recordings promote a more engaging make-up experience for absent students.

Although I developed many of these approaches during hybrid/remote learning, I have continued using them with in-person teaching to support in-class labs and extend the overall lab experience.

Acknowledgements

Thank you to Laurie Smith for her collaboration in developing some of these activities. Thank you also to Jacquelyn Blum and Tom Holt for their feedback and ideas on labs.

References

1. Activity adapted from https://www.thoughtco.com/make-a-density-column-604162 (accessed Feb 20, 2023).

2. Activity adapted from https://www.bbc.co.uk/bang/handson/lightspeed.shtml (accessed Feb 20, 2023).

3. Activity adapted from https://www.instructables.com/Candle-Experiments-and-Explorations/ (accessed Feb 20, 2023).

4. Pivot Interactives was acquired by Discovery Education, worldwide edtech leader whose state-of-the-art digital platform supports learning wherever it takes place, in August of 2022.

Photo credit:
(article cover) Bigstock.com/adresia.stock