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May 2021 | Nuts & Bolts
Chemistry Experiments at Home
By Kathleen Dwyer
Figure 1. Labeled material bags provided for students to use at home.
When the pandemic forced all educators to revise their teaching practices, chemistry teachers faced a unique set of constraints. Laboratory experiments are at the core of chemistry instruction, affording students an opportunity to observe phenomena and test hypotheses.
Providing similar experiences in a virtual environment, however, poses considerable challenges. In response, some teachers have decided to use simulations for labs and demonstrations. Others have shared videos that are available online or ones that they created themselves. I chose another solution: to have students perform their own experiments at home.
Attaining support and permission
Before pursuing this course of action, I discussed my plans with other chemistry teachers. Several expressed their desire to provide home lab experiences, but shared that they could not obtain permission from their school or district. I felt fortunate to work in a district that not only supported, but also applauded my choice. Both my principal and superintendent gave their full approval and asked what they could do to assist.
To protect the district from liability, I was asked to speak with the school district’s attorney. We discussed the strategies that I would use to ensure safety and keep parents/guardians informed. To begin with, I would label materials with messages about potential hazards, e.g., sharp edges or the consequences of improper disposal. I would also provide online links to SDS sheets for all chemicals. Last but not least, I would send frequent emails with advance notification of the materials to be used that week, potential hazards associated with each item, and safety precautions to follow for risk mitigation.
When chemistry classes were in person, I began each fall semester with a review of safety rules, and required students and parents to sign a safety contract to ensure they understood expected behavior.
For the virtual course, I allowed parents/guardians to grant permission electronically. To enable them to give informed consent, I sent them a copy of the safety contract and a list of the materials to be used. All of my families agreed to the proposed terms. If any had declined, I was prepared to offer those students an opportunity to pair online with a lab partner, enabling them to participate in the activities.
Figure 2. Materials provided for an at-home Mystery Powder lab.
Anticipating that virtual learning could last several months, I planned experiments for the first quarter. The pandemic decreased income for many families and the CDC was encouraging people to minimize trips to the store. To ensure all students had equal ability to participate, I provided materials for every student, including even common household objects. For example, chemically changing an egg’s shell only requires an egg, vinegar, and a cup. I knew I couldn’t ask families with food insecurity to supply these food items for chemistry experiments.
I placed materials for each activity in a zipper lock bag labeled with the name of the experiment, the specific materials enclosed, and potential hazards (see Figures 1–5 and Table 1). I also placed the components within the baggies in clearly marked individual containers. I used microcentrifuge tubes for smaller amounts of chemicals, such as powders or metal shavings, and condiment cups with lids for larger quantities of substances such as baking soda, sugar, and salt. Preparing and labeling these items took a great deal of time, but it was necessary to ensure that students could easily identify and safely store all materials.
Baking soda (1 oz)
Corn starch (1 oz)
Chalk (1 oz)
Plaster (1 oz)
Salt (1 oz)
Sugar (1 oz)
Unknown mixture of powders
Vinegar (8 oz)
Universal indicator (1 mL)
Wooden stirrer (6)
Plumbing damage if improperly discarded
Powders irritate lungs if inhaled
May irritate skin
Figure 3. Materials provided for an at-home Reactivity of Metals lab.
By carefully selecting inexpensive items, I managed to keep the cost of the materials for dozens of activities at about ten dollars per student for the semester, which I paid for using the annual science department budget.
For example, I discovered inexpensive alternatives for traditional lab supplies, such as using artist paint trays instead of well plates, or trimming the bulb of a pipette to turn it into a miniature spatula. I also used common household chemicals for most activities.
In the classroom, students compare the reactivity of metals and nonmetals using dilute hydrochloric acid. For their home experiments, I learned that vinegar worked just as well for students to observe these reactions. In addition, I adapted demonstrations to give students similar observations on a smaller scale. As an example, the Hoffman apparatus is used to demonstrate the electrolysis of water. At home, I had students place two thumbtacks through a plastic cup, fill it with water, then place a 9-volt battery underneath the apparatus. While they could not precisely measure the 2:1 ratio of gases generated, they could readily observe that different volumes of hydrogen and oxygen were produced.
In August, I assigned students with appointment times to come to the high school to obtain books and materials for their virtual classes. I used this as an opportunity to meet each student in person, while they collected their supplies. Most students came as scheduled, and I provided ‘porch delivery’ for those required to quarantine at home.
Managing the hands-on experience at home
Just as would be done at school, every activity at home began with a review of safety considerations. Some new safety issues emerged that do not exist in the classroom. For example, I can easily monitor the use of eye protection in person; but in a virtual setting, I had to require students to turn on their cameras to verify their use of safety goggles. I provided these along with the other materials, but students had to store and locate them when needed.
There were other modifications I needed to make to my standard procedures. For example, students who stayed in multiple locations needed advance notice of which materials would be required for the upcoming week. In addition, at school, materials are safely stowed and protected, students are taught why food and drinks should be kept out of the chemistry laboratory, and are shown the correct method and location for disposal.
In contrast, students at home needed to take responsibility for keeping their materials out of the reach of smaller children and pets, and often did not have the luxury of an area set aside for experiments, so I needed to remind them to keep food and drinks separate from where they were working, and about which materials could be safely discarded in the trash and which would have to be retained for disposal at school. For example, salt water can be safely washed down the drain, but to avoid potential plumbing problems, I instructed students to return any mixtures with glue or plaster to a sealed plastic bag.
Modifying traditional classroom labs
Figure 4. Example of a homemade balance.
I used different types of activities to provide laboratory lessons, including observations, inquiry, challenges, and construction. To make mass measurements, for instance, students created a homemade balance (see Figure 4). A ruler pivoting on a straight pin was placed on the ends of a clothespin attached to a box. First, they suspended two paper cups using paper clips (each with a consistent 0.5 gram mass) on either side of the ruler. I had students use grains of rice for more precise measurements. I discovered the directions for this balance at topscience.org , a highly recommended resource for science activities using simple, readily obtained objects.
I used an electronic balance to measure the mass of metal samples and challenged students to use their homemade balance to match the values I provided. To my surprise and delight, many students were able to accurately measure their sample to within a few hundredths of a gram. I gave each student a different coded sample, so all were accountable for performing their own experiment. They created videos of their balance in operation and offered suggestions to classmates to improve their devices.
Figure 5. Materials provided for an at-home Density lab.
I had the students use centrifuge tubes as inexpensive alternatives to graduated cylinders. The students placed a piece of lab tape on the side and made smaller markings between the larger graduations to make more precise measurements. With the ability to make mass and volume measurements, students were able to complete traditional density labs. They calculated the density of zinc washers, copper tubes, and brass screws, then used that data to determine for the composition of pennies (see Figure 5). Density values provided evidence that older pennies contain more copper, newer pennies have more zinc, and pennies that look gold are actually made of less expensive metals.
The students also used their homemade balances to determine the percent composition of a mixture. I gave each student a sample containing salt, sand, iron filings, and foam beads. After observing the properties of each, students developed a procedure to separate and measure each component. They strived to accurately determine the known percent composition of their coded sample.
Some activities asked students to solve mystery challenges. For instance in one activity, they had to test the properties of different unknown white powders in order to identify them. Similarly, I had them combine unknown clear solutions to determine which substances were the same and which were different. Other activities required sleuthing to determine cause and effect, such as What made beads change color? What made the fortune fish move? and Why did one nail rust while the other did not?
In several labs, I asked students to test the properties of materials and design improvements. Combining glue and borax solution is a common activity that creates slime. I asked students working at home to determine the best ratio of ingredients for a selected property, such as the stickiest product or the one with the best flow. I introduced materials science by having students make concrete. Students added different aggregates to cement mix: e.g., hay, gravel, or bobby pins. They combined the materials in Styrofoam bowls and evaluated the final products using drop tests. Many related concepts emerged from this inquiry experiment: the function of rebar for reinforcement, the economic advantages of aggregate addition, and the carbon footprint associated with concrete construction.
A positive experience
Student response has been overwhelmingly positive. As one stated, “I don’t connect to videos or simulations the way I do when I mix things myself.” At a time when many teachers were struggling to engage students in virtual classrooms, I found that offering at-home experiments led to excellent student attendance and engagement.
Parents worry that their children spend too much time on electronic devices, a concern exacerbated by virtual instruction. I received messages of appreciation from many parents for these lessons that reduced the amount of time students spent on computers. Some worked together on the activities, conducting the experiments and learning as a family.
While I created these modified experiments out of necessity, the benefits gained from this experience will continue to improve my practice in the future. I discovered greener and safer alternatives to traditional labs.
Students made better connections between the content and everyday life. The rate of completion was higher for at-home labs than traditional homework. The biggest challenge was preparing the materials to be used. I spent a great deal of time planning, purchasing, and preparing numerous items for over 100 students. It was well worth the effort, however, as students were highly engaged and learned from the experiments they conducted at home.
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