Water You Thinking? Bringing the Chemistry and Biology of Water to Middle-Schoolers

Dean J. Campbell, Rhiannon Davids, Michelle Fry, Michelle Edgcomb-Friday, Logan Harrington*

*Bradley University, Peoria, Illinois

For many years, Bradley University in Peoria, IL, has had connections to the Detroit Area Pre-College Engineering Program (DAPCEP). As the website for the program states: “DAPCEP’s mission is to increase the number of historically underrepresented students who are motivated and academically prepared to pursue degrees leading to STEM careers. We achieve this with supplemental academic programs for Pre-K to 12th grade students by partnering with schools and universities to develop and facilitate engaging curriculum. We are driven to increase the number of students who graduate from high school and pursue degrees and/or careers in STEM fields and serve 11,000 students annually.”¹ Bradley University began its collaboration with DAPCEP in 2018. For DAPCEP in Peoria, participants from local middle and high schools can attend STEM-related short courses covering a variety of topics. The courses are held in the fall and spring semesters, with each course running for five consecutive Saturday mornings. This writeup describes one of these courses, called “Water You Thinking?”, where the theme of water was used to connect a number of concepts in the area of chemistry and biology. Some objectives for this course were to introduce students to:

• fundamental concepts in chemistry, biology, and related sciences and mathematics
• how various topics can be explored from the different perspectives of complementary disciplines
• some careers using the STEM fields of chemistry and biology

Why water as a theme? Water touches almost every aspect of our lives and is a relatable substance for students of all ages. Over the five weekends of this course, students explored

1. general physical and chemical characteristics of water

2. hydrophilic and hydrophobic molecules and their properties in water systems
3. how the presence of water-soluble metabolites in urine samples can help medical professionals diagnose diseases
4. surface water quality and how it relates to urban, agricultural, and wetland landscapes
5. how terrestrial animals cope with water loss and how the body forms of aquatic animals are designed for movement and support in water

The course was run in Fall, 2022, and Spring, 2023, and had about ten 4^th-7^th graders each offering. The primary evaluation methods were pre and post-test assessments given near the beginning and near the end of the course. The students were encouraged to verbally participate in class, and had the opportunity to participate in hands-on activities.

The content question used in the assessments included (answers in bold):

Q: Water molecules look like someone. Who?

• Dr. Campbell
• Batman
• Mickey Mouse
• Baymax

Q: Will salt dissolve in water or oil?

• Water
• Oil

Q: Which tissue in your body most relies on calcium for proper formation?

• Brain
• Skin
• Liver
• Teeth/bones

Q: What type of substances might be found at high levels in urine (pee) if someone is diabetic and not taking medicine to control it?

• Salt
• Blood
• Sugar (glucose)

Q: Which of the following tests provides the best indicator of salt pollution in surface waters?

• pH
• Turbidity
• Conductivity
• None of these

Q: What is special about the eyes of squids?

• They are entirely lenses
• They are shaped like squares
• They release ink

More detailed descriptions of what was covered in each week of the course are provided below.

 

Week 1 – What is water? Structure and properties of water and its solutions

The first week of the course covered general physical and chemical characteristics of water. Many of the activities done this week have been used in undergraduate chemistry courses at Bradley University, and videos related to many of these activities can be found online.^2-5 For class the first day, many of the students arrived a little late, so they were given UV bead bracelets to assemble while waiting. UV beads are photochromic beads that change color when they absorb UV light and some of their bonds break. At the beginning of the class, they did pre-survey questions and watched the welcome video from the project director. They were also shown various facilities in the science building, including the lecture hall named after Major Robert Lawrence, America’s first Black astronaut. After a brief safety discussion, the presentations led off with a goldenrod paper welcome sign. This paper changes from yellow to red when sprayed with basic ammonia solution, and back to yellow when sprayed with an acidic vinegar solution.

The first main topic covered the solid, liquid, and gaseous states of matter. Squeezing a bottle of gaseous air and a bottle of liquid water illustrated that gases are compressible but liquids are not. Density of gases vs liquids were illustrated with water and air in a bottle, and the varying density of liquids were illustrated with oil and water in a bottle. Then, the game “Will it float?” was played, where various solid objects were placed into a large transparent tub of water after students made predictions whether they would float or not. Samples included an aluminum cable (an example of a metal that is denser than water and bendable), a ceramic tile (an example of a ceramic that is denser than water and brittle), and a plastic frisbee (an example of a plastic that is less dense than water and flexible). The information is usually sufficient for students to figure out which material (plastic) tends to be in the floating oceanic garbage patches around the world. Finally, a bowling ball (less than 12 pounds) is floated on the water to reinforce the idea that big and heavy does not necessarily mean dense.

Next, the students moved on to an activity that modeled electron arrangements in atom and molecules, using milk caps representing electrons in plastic trays representing atoms with available locations for electrons. A previous post has described these types of models and ideas, using milk caps placed in egg crates.⁶ The trays representing atoms here were used in packaging small quiche tarts, and had arrays of four dimples by six dimples. A single tray could therefore be used to make a model of one oxygen atom that was four dimples by four dimples, and two models of hydrogen atoms that were each two dimples by two dimples. Some dimples were labeled as being associated with atomic nuclei and shielded with pieces of plastic to prevent addition of milk cap electrons to those locations. The open dimples were places that the milk caps could be added. In the activity, students worked with partners to build models of individual atoms of hydrogen and oxygen, hydrogen and oxygen molecules, and water molecules. The main goal of these models was to show how atoms bond together by sharing electrons and how the atoms in hydrogen and oxygen molecules can be rearranged to make water molecules. Some student groups struggled with building the structure of water, but some groups did fine. Most, if not all, students had some previous knowledge on basic parts of an atom. Figure 1 shows the milk cap models of hydrogen atoms, an oxygen atom, and a water molecule.

Figure 1. Milk cap models of electron distributions and bonding in hydrogen atoms, an oxygen atom, and a water molecule.

 

To accompany the activity, various gas samples were electrically excited to produce colors that were characteristic of their elements, in order to illustrate that atoms have differences in electronic structure. Students were also shown a model fuel cell car that contained a hydrogen-oxygen fuel cell providing electricity to move a motor and wheels. The hydrogen and oxygen gases had been produced by using external batteries and the same assembly to electrolyze water. The students then moved on to do a guided aqueous electrolysis experiment where they placed pencil electrodes connected to a 9 V battery into an aqueous solution of magnesium sulfate and universal indicator. Figure 2 shows the electrolysis setup, with oxygen gas and hydrogen ions produced at one pencil tip and hydrogen gas and hydroxide ions produced at the other pencil tip.

Figure 2. Electrolysis of water containing magnesium sulfate and universal indicator, using electricity produced by a 9 V battery.  

 

From here the discussion transitioned to fundamentals of acid and bases, which are often associated with aqueous solutions. One demonstration was blowing bubbles in indicator in water, where human breath was bubbled into water containing universal indicator. The carbon dioxide gas reacted with the water to produce carbonic acid which changed the color of the indicator. This was done to show that carbon dioxide can behave as an acid when mixed with water. Also, there is a connection to increasing carbon dioxide in atmosphere dissolving into oceans and making it more difficult for sea life containing calcium carbonate shells to survive. The carbon dioxide concentration in the atmosphere was illustrated by LEGO atmosphere sticks.⁷

Another acid base demonstration shown was the slow antacid, where vinegar (acetic acid) was slowly added to milk of magnesia (magnesium hydroxide suspension) and universal indicator in water. The purple or blue color of the indicator in the basic suspension changed through the colors of the rainbow to pink or red as the acidic vinegar was added. However, if only a small amount of vinegar was added at a time, excess solid magnesium hydroxide dissociated to make the solution basic again. If enough acid was added, either vinegar or some other acid, the magnesium hydroxide was completely consumed and the mixture stayed red. Other demonstrations involving acids, bases, and carbon dioxide included the classic vinegar baking soda volcano where vinegar and sodium hydrogen carbonate reacted to produce carbon dioxide, and seltzer poppers. Here a half-tablet of Alka-Seltzer (containing citric acid and sodium hydrogen carbonate) was placed into a Fuji-style film canister filled halfway with water and closed. The water dissolved the tablet and allowed the components to react to form carbon dioxide gas, water, and sodium citrate solution. After 10-30 seconds the carbon dioxide pressure built up and popped the canister apart. Carbon dioxide dissolved in water was demonstrated by adding Mentos to soda to assist in its outgassing. This was a popular activity.

Liquid nitrogen demonstrations were shown as a finale for the day’s activities. These included boiling liquid nitrogen (liquid to gas phase change) in a whistling teakettle or in a fountaining tube. A plastic bottle of air was shrunk in the liquid nitrogen to illustrate gas behavior. Racquetball jingle bells and soft-to-brittle polypropylene cups were cooled down through their glass transition with liquid nitrogen to illustrate that solid to solid phase transition. Finally, excess liquid nitrogen was poured into soapy water to make cold foam, again showing the liquid to gas phase change.

 

Week 2 - Water-loving and water-fearing: hydrophilic and hydrophobic

The second week of the course covered hydrophilic and hydrophobic molecules and their properties in water systems. As in the first week, many of the activities done this week were have been used in undergraduate chemistry courses at Bradley University, and videos related to many of these activities can be found online.^2-5 The class began with descriptions, models, and examples of solid crystal structures, including the ionic compounds sodium chloride and calcium carbonate. (One problem was that a child or two attempted to draw on the lab table with the calcium carbonate crystals, so these might be better distributed near the end.) The model of water ice was connected to snowflake pictures and a Snowflake Bentley book. Crystal growth was shown using reusable heat pack sodium acetate hand warmers, containing supersaturated sodium acetate solution. When the metal disk inside was flexed, it became a nucleation site for the exothermic formation of crystals of solid sodium acetate. Another activity done with the students was spontaneous assembly of soda straws, where short lengths of soda straws were floated at the surface of water assembled into a two-dimensional rectangular array. This was used as a macroscale analogy for the formation of ordered solid (a crystal) from disordered liquid or solution. After the brief description to ionic compounds, the class moved into ionic solutions. The students and helpers placed various ionic compounds into water and monitored temperature changes of the solutions with a Vernier system equipped with a thermometer. Sodium chloride, magnesium sulfate, and sodium hydrogen carbonate made the solutions cooler, whereas an ice melting mixture of sodium chloride and calcium chloride made the solutions warmer. The impact of ionic compounds on osmosis was illustrated with baby carrots in regular vs salt water, where students found that a carrot that had been soaked overnight or longer in tap water was crisp and a carrot soaked overnight or longer in salt water was soggy. This was done to show osmotic pressure in cells. Carrots that were frozen and then thawed into soggy sticks were also shown to depict cell wall damage. Similarly, Orbees beads were swelled in water. Here, sodium polyacrylate beads had absorbed water, which made the polymer beads swell. This was done to show ion-dipole attractions that occur when ionic compounds and water interact. The beads swell more in pure water than they do in salt water.

The class moved to coverage of molecular polarity and hydrophilic, hydrophobic, and amphiphilic substances, including models of water, hexane, and soap molecules. Two-phase bottles reinforced these concepts, showing a plastic bottle containing a layer of yellow corn oil over a layer of water with blue food coloring.⁸ When the bottle was shaken, the phases mixed. When the bottle became still, the phases separated again. Students were also shown a plastic bottle containing a layer of yellow corn oil over a layer of water with blue food coloring, all with a little bit of dish soap added. When the bottle was shaken, the phases mixed. When the bottle became still, the phases eventually separated again, but much more slowly than when soap was not added. This was done to show polarity, solubility, the idea of “like dissolves like”, and the amphiphilic nature of soap. Following this, the students participated in the color changing milk experiment, where dish soap was added to food coloring drops on milk to mix the colors in a swirling pattern.⁹ Pepper was sprinkled over the milk before the soap was added so that the soap pushed the pepper across the polar milk.

Another demonstration of polarity was placing water drops on sooty vs. clean metal pipes. The water was attracted to the polar metal pipe surface, but rolled much more easily down a nonpolar sooty surface. Students were given paper snowflake models of graphene to represent a portion of the soot structure. After it was noted that graphene has been possibly found in space, a short biography sheet of Major Robert Lawrence (Bradley University alum and the first black U.S. astronaut) was given to the students. Other polarity demonstrations included the color changes of iodine between polar water (yellow-brown) and the nonpolar interior of starch-like molecules (purple-black), was shown using tincture of iodine and spray starch, with Vitamin C added later, and also with a counterfeit money detection pen on paper. The students moved on to exploring the wetting behavior of water on polar and nonpolar surfaces. Water droplets spread out on polar surfaces like paper and the interior cut surfaces of fruit. Water droplets beaded up on nonpolar surfaces like waxed paper, some leaves, and the exterior surfaces of fruit.

From here the idea of “like dissolves like” was again explored in the context of solvent swelling and solvent welding polymers. Orange oil damaged nonpolar polystyrene knives, and acetone could be used to solvent-weld the knives. Water could weld starch-based but not polystyrene-based foam packing peanuts. Water could solvent weld noodles, but less polar solvents could weld polylactic acid strands. The students had the opportunity to try to make a dry erase marker person float on water. They used a dry erase marker to draw a stick figure of person on a smooth plastic surface. They placed the plastic in water to lift the figure off the plastic and float on the surface of the water. This was done to show that the nonpolar figure did not dissolve in the polar water. Finally, in the time remaining in the class session, the students were able to revisit the wetting behavior of drops of water, this time on heat shrinkable sheets of polystyrene plastic. These Shrinky-Dinks were nonpolar both before and after shrinking. This activity was very popular, and students would have spent more time if allowed.

 

Week 3 – Water within: Water in human health

The third week of the course had a Medical Laboratory Science theme, connecting water to human health by testing artificial urine samples and using the results to diagnose mock patients. There is a shortage of Medical Laboratory scientists in the field, and students were encouraged to look into the career. The class started with two quick videos, about ten minutes in total, describing the career.^10,11

Students performed mock urinalysis experiments based on a kit from the Aldon Corporation (Avon, NY).¹²  The students were given detailed step-by-step instructions that included tables for collection of data from each test run. Each student team was given four simulated urine samples, including three test subjects (“X”, “Y”, and “Z”) and one control (labeled “C), and pH indicator strips to test for sample pH. The student teams were provided with dropper bottles containing the appropriate reagents to run diagnostic “wet” chemistry tests on the simulated urine samples to detect the presence of protein (Biuret test), reducing sugar such as glucose (Benedict’s test), and calcium (Sulkowitch test). All of the reagents used pose potential risks as irritants if exposed to skin or eyes and, as such, students were required to wear proper personal protective equipment (i.e. lab safety goggles and latex or nitrile gloves) provided at all times. Waste disposal was handled by the instructors. 

Each of the simulated urine test samples was designed to give a positive response for one of the diagnostic tests, providing the opportunity for a group discussion of what that positive reaction could mean in terms of health and disease diagnosis. Diagnostic multi-parameter urinalysis reagent test strips were provided to allow testing of each sample for multiple disease biomarkers and to allow comparison of the results obtained by the two different methods for pH, glucose, protein, and calcium ions. Finally, the group discussed the results obtained and collectively “diagnosed” the mock patients as being at risk for one of three possible conditions: microbial infection, bone disorders, or diabetes mellitus.

 

Week 4 – Water in the environment: How water at the Earth’s surface affects us

The fourth week of the course covered surface water quality and how it relates to urban, agricultural, and wetland landscapes. The class started with a science thought experiment adapted from a lesson on the nature of science.¹³ Each pair was given a manila folder containing puzzle pieces. They could then pull out a handful of pieces. The students were asked to raise their hand and provide observations of what they saw as well as their hypotheses of what was in the jigsaw picture. Students struggled a little with separating observations from inferences, terms that were introduced and explained during the activity. Several rounds of drawing puzzles pieces and making observations were used to refine students’ hypotheses about the jigsaw puzzle picture. Students then were allowed to look at each other’s puzzle pieces. This was done to support group discussion on nature of science, including the importance of data and the collaborative nature of scientific work. They then decided if they thought they were working on the same puzzle. From the activity and through discussion, they drew conclusions on what the full picture looked like which were largely correct. They also discussed the limitations of their conclusions even when shown the full picture, e.g. their ability to distinguish between sunrise and sunset. This led to further discussion on how personal experience can influence interpretation of data.

For the next activity students were given plastic water molecules that used magnets to model hydrogen bonds. Students were able to discuss the “stickiness” of water molecules before moving on to the next part of the activity, which involved water and waxed paper. Students were given a beaker of tap water and a plastic pipette. They were to put droplets of water on the waxed paper and see what happened. This was another exploration of polarity and surface tension. Students had a blast with this and noticed that water would group together and create “bubbles” on top of the waxed paper. Students would have happily pursued this activity for as much time as they were given, although oversaturation and a thoroughly wet table provided a natural end point. To the instructors’ surprise, the students had greatly retained the lesson on polarity two weeks prior and remembered the vocabulary words. They brought them out on their own without prompting and used the experience to determine that the wax paper was hydrophobic. They were then asked to think of environmental substances that might dissolve in water and others that would not. They used their retained knowledge on hydrophobic and hydrophilic substances to make their own suggestions and explanations, albeit not always completely correctly. This strong retention surprised the instructors and greatly helped the rest of that lesson. Students were, through the lesson, introduced to the new words polar and non-polar and those were connected to hydrophilic and hydrophobic, which they brought to the table themselves. Overall this activity went very well, and showed the students’ ability to use higher level thinking.

In preparation for the final activity, students participated in a discussion on the water cycle. The students again showed very good recall and surprisingly in-depth knowledge of the parts of the water cycle. Some students had studied it recently in school, and therefore had the effect of having more knowledge on vocabulary terms, like infiltration and surface run-off, than the undergraduate helpers. 

This discussion of the water cycle and of polar and non-polar substances were paired with an exploration of the local area using Google Earth. Students looked at various landscapes within the city and predicted where water would run-off, what environmental contaminants might come in contact with the water, and how that might impact the quality of local river water. The inclusion of Google Earth was very popular and the instructor allowed students to suggest public places to map, but not private residences.

Participants were then introduced to three tests of water quality: conductivity, pH, and turbidity. Through group discussion, the terms were defined and participants learned what type of pollutants influenced the three measurements in surface water. Participants were then given pre-made aqueous solutions of either sodium chloride, sodium bicarbonate, dilute lemon juice, or starch to test using Vernier sensors and pH paper. Finally, they were given an unknown solution (e.g., a solution of starch and sodium chloride) and asked to test the sample and hypothesize what type of environmental contaminant was most consistent with their results. This allowed DAPCEP students to connect the discussion of the water cycle and the Google Earth activity with the water quality testing. Students were able to make realistic hypotheses regarding possible effects of road salt and erosion. Their ability to connect information across all aspects of the day’s lesson was impressive especially considering the number of concepts explored in a short timeframe.  

By happy coincidence, the biology class that used the lab space during the school week was working with sea monkeys (brine shrimp). The DAPCEP students were interested in them, and an undergraduate who stopped by was gracious enough to talk to the students and to explain what they were doing. The students had a lot of interest and questions, making this ecology lab exploring the impact of temperature and pollution on brine shrimp hatch rate to be an excellent fit to the rest of the day’s activities.

 

Week 5 – Living with water: How plants and animals have adapted to use water

The fifth week of the course covered how terrestrial animals cope with water loss and how the body forms of aquatic animals are adapted to movement and support in water. The class began with a discussion on the connections between water and life on Earth, and a discussion based on how different organisms take in oxygen, using the examples of humans, catfish, and frogs. The class compared the breathing apparatuses for different classes of animals (fish, amphibians, reptiles, birds, and mammals) and discussed how the life cycle of frogs are unique within the animal kingdom. This discussion led into talk of tardigrades and their tolerance to some of the most extreme conditions, including the vacuum of space. After showcasing these unique organisms, the dehydration/rehydration processes that allow them to survive almost indefinitely were explained. The students then worked with microscopes to actually observe living tardigrades with the students. This allowed the students to get some hands-on experience with a common tool in biology labs that many had never used before.

After the tardigrade observation, the class began discussion surrounding squids in the environment (focusing on their camouflage, good eyesight, and ink defense), their anatomy and physiology (invertebrate, and their entire eyes are lenses), and safety talk in regards to animal dissections. The basic structures contained within squids and humans were compared, particularly between gills/lungs and hearts present in both organisms.

During the dissection of the squids, Figure 3, the students were allowed to explore with one another, asking questions as they went. This allowed the students to be exploratory in their learning while also working at their own pace. There was a diagram projected on the board showing the basic structures of squids, but the students were encouraged to identify different parts on their own as well as infer the functionality of structures, particularly in reference to their location within the organism. A belemnite fossil was shown to students for comparison to live squid. This exploratory dissection was approximately an hour in length, so it really allowed all of the students to ask their questions, use the tools provided if they wanted to, and to interact with their peers in a productive and educational environment.

 

Figure 3. (LEFT) Dissecting a modern squid. (RIGHT) Belemnite fossil.  

 

 

Safety

The instructors have worked to maximize safety, but each demonstration and prop comes with its own particular set of safety considerations. All of the reagents used pose potential risks as irritants if exposed to skin or eyes and, as such, students were required to wear proper personal protective equipment (i.e. lab safety goggles and latex or nitrile gloves) provided at all times. Waste disposal was handled by the instructors. If physical classroom examples are to be done in-person, then instructors must identify and respond to potential hazards, personal protective equipment, and disposal issues associated with these examples.

 

Acknowledgements This work was supported by the Detroit Area Pre-College Engineering Program (DAPCEP) and Bradley University. We especially thank Jacqueline Henderson for leading this program at Bradley University. Some additional support was provided by the Illinois Heartland Section of the American Chemical Society and the Illinois Space Grant Consortium.

 

References

1.   Detroit Area Pre-College Engineering Program. DAPCEP: Our Mission. https://www.dapcep.org/mission/ (accessed July, 2023).

2.   Campbell, D. J. “A Demo A Day: Demonstrations and Props Used in My General Chemistry Class.” ChemEd Exchange. January 17, 2022. https://www.chemedx.org/blog/demo-day-demonstrations-and-props-used-my-g... (accessed July, 2023).

3.   Campbell, D. J. “A Demo A Day II: Demonstrations and Props Used in My Environmental Chemistry Class.” ChemEd Exchange. December 3, 2022. https://www.chemedx.org/blog/demo-day-ii-demonstrations-and-props-used-m... (accessed July, 2023).

4.   Campbell, D. J. “A Demo A Day III: Demonstrations and Props Used in My General Chemistry II Classes.” ChemEd Exchange. December 3, 2022. https://www.chemedx.org/blog/demo-day-iii-demonstrations-and-props-used-... (accessed July, 2023).

5.   Bradley University Chemistry Club. Demo Videos. https://sites.google.com/mail.bradley.edu/bradleychemdemos/demo-videos (accessed July, 2023).

6.   Campbell, D. J. “Hatching Ideas to use Egg Cartons to Represent Electron Arrangements.” ChemEd Exchange. January 23, 2023. https://www.chemedx.org/blog/hatching-ideas-use-egg-cartons-represent-el... (accessed July, 2023).

7.   Campbell, D. J. “LEGO Brick Atmosphere Sticks.” ChemEd Exchange. June 6, 2021. https://www.chemedx.org/article/lego-brick-atmosphere-sticks (accessed July, 2023).

8.   Campbell, D. J. Chem Demos You Tube channel. Two phase "wave" bottles demonstrate density, polarity, and soap. https://www.youtube.com/watch?v=jASD-xooP2E (accessed July, 2023).

9.   Steve Spangler Science. Color Changing Milk Experiment – Magic Milk Experiment. https://www.stevespanglerscience.com/lab/experiments/milk-color-explosion/ (accessed May, 2023).

10.  ASCP. Your Health, Your Laboratory. https://www.youtube.com/watch?v=djCnLTLmLuc&t=6s (accessed July, 2023).

11.  Nebraska Medicine Nebraska Medical Center. My Job In A Minute: Medical Laboratory Scientist – Nebraska Medicine. https://www.youtube.com/watch?v=IlKTVibaciE (accessed July, 2023).

12.   Aldon Corporation. Innovating Science® - Urinalysis Using Simulated Urine. https://www.aldon-chem.com/product_urinalysis-using-simulated-urine.php (accessed July, 2023).

13.   WGBH Educational Foundation. “Solving the Puzzle.” Evolution: A Journey into Where We’re From and Where We’re Going, Teacher’s Guide. 2001.