Stephen C. Kissel
Gum Lab
This lab provides students with practice using a triple beam balance to determine mass. They predict whether the mass of a piece of chewing gum will increase, decrease, or stay the same after it has been chewed for several minutes. Also noted are any changes in color, shape, texture, smell, or taste of the gum. After the data is gathered, students need to explain why their gum lost mass.
A similar lab could provide students with practice determining volumes. Students could measure the dimensions of a block of wood to determine its volume. They could estimate whether a beaker or test tube has a greater volume and figure out how to prove their prediction. Proper use of a graduated cylinder would need to be taught with an emphasis on taking the measurement at the bottom of the meniscus and reading it at eye-level. Students could also use the water displacement method to determine the volume of an irregular-shaped object, such as a rock. Furthermore, they could even blow into a hose submerged in a water-filled graduated cylinder to discover lung capacity.
Is Air Matter? Lab
This lab provides students with a hands-on experience that reinforces the definition of matter. They state whether they think air is matter and explain why they came to that conclusion. The volume of a balloon is estimated when it is bunched and empty as well as filled. They try to fill the balloon partially placed in a 2-liter bottle without and then with a straw beside the balloon. Then they mass the balloon when it empty and filled. After the data is gathered, students need to explain why air is indeed matter.
Previous to this lab, a discussion of what is matter and what is energy should take place. During that discussion, students should also be challenged to decide how to categorize thoughts and emotions. What is love? The talk can also include discourse about the energy in our bodies and what happens to it when a person passes away. Energy cannot be created or destroyed. The dialogue will be meaningful
A demonstration of crushing a can using atmospheric pressure can accompany this lab. A small amount of water can be boiled in a soda can. When steam appears, the can should be turned over into a shallow container of cool water, sealing the top of the can. The steam condensates on the inside of the can creating a vacuum, which causes the can to crush instantly.
An additional lab would have to do with flammability. Caution needs to be a priority when working with a flame. Furthermore, care should be taken to not set off a fire alarm or sprinkler system. The preferred venue for working with a flame would be outdoors. If that is not possible, at a minimum the lab should be practiced by the instructor outdoors before performing it indoors. Then the instructor would be familiar with what to expect. Partially opened windows can provide ventilation and a means for smoke to leave the classroom, as well. A prediction can be made as to whether the masses of paper and fine steel wool will increase, decrease, or stay the same after being burned. Matches can be used to light each sample in a small aluminum container. A 9-volt battery could also be used to light the steel by making contact with the terminals. An explanation of why the mass of the steel wool increases should include the topics of oxidation and rust.
A couple of flammability demonstrations incorporate corn starch. It is preferable to perform each outdoors with students a safe distance away. If that is not possible, the instructor should first practice them outdoors to become familiar with what to expect. For one, 1.5 meters of tubing is inserted into the lowest point on the side of a gallon paint can. The tubing is inserted about a centimeter. Some corn starch is piled inside the can, in front of the tubing. Opposite the pile is placed a couple of short candles seated on a piece of wood to elevate them. The candles are lit and the lid, which has been punctured and tied to the can, is placed on top of the can closing it. When air is blown through the tubing and into the can it disperses the corn starch throughout the can, and it rapidly burns. A large flame will pop the lid off the can.
For another demonstration, a meter of plastic tubing can be affixed to the length of a gas grill lighter along its top. The end of the grill lighter should extend about a centimeter beyond the end of the tubing. The tubing can be filled with corn starch by squeezing it in with a plastic condiment bottle. The lighter is clicked on and the flame should point up and be in front of the tubing hole. When the corn starch is then quickly blown through the tubing, it will ignite as it passes over the flame and shoot forward as a much larger flame. In connection with these two demonstrations of a chemical property, flammability, discourse about the dangers involved with the storage of grains and other powdered materials will be meaningful.
Corn Starch Lab
This lab challenges students to classify whether a substance is a solid or a liquid. Corn starch is mixed with water in a 1:1 ratio and a 1:1.5 ratio. The mixtures are poked, prodded, squeezed, and held to analyze and compare them. Interestingly, students will find that the 1:1 ratio acts like a solid and a liquid at the same time. After the data is gathered, student are asked to predict whether 1:0.5 and 1:2 mixtures will be liquids or solids.
Another lab that touches on states of matter can be done with dry ice. The masses, over a ten minute span of time, of beakers filled with a combination of water and ice as well as water and dry ice are compared. After the data is collected, students need to explain why the breaker of water and dry ice lost mass. A discussion of sublimation and condensation need to be included. Carbon dioxide is colorless and the condensation of water vapor is what is seen. Students need to explain why frozen carbon dioxide is called “dry” ice. It skips the wet liquid stage when it goes from a solid to a gas. Activities with dry ice can be included, as well. Sliding dry ice, placing it in warm water, placing it in soapy water, placing it in a closed film canister, pouring it over a lit candle, and pushing a coin into dry ice are only a few of many things you can do to create interest and discourse.
Along with these labs, states of matter can be analyzed using virtual interactive simulations found on the PhET website provided by the University of Colorado. Registering as a teacher is easy and free.
Some demonstrations can be performed related to heat transfer. A flask of freezing blue water can be placed in the tank. Even if on its side, that water would not spread far. A similar tiny flask containing boiling red water could be placed in a tank or room-temperature water. It should be noted that the hot water rises to the surface where the water is the coolest because heat travels from hot to cold objects. Pepper could be placed in a beaker and then heated. Convection would circulated the flakes. An empty Bigelow tea bag could be placed vertically on one palm and then lit. As the flame lowers it will be lifted by a convection current before the hand is burned. A plastic and metal spoon could be placed in boiling water. If the handles are touched, the metal one will be hot due to conduction.
Density Lab
This lab gives student experience solving problems. Previous to this lab, students have been taught that density equals mass divided by volume. They find the density of a liquid by determining its volume and mass. They also find the density of a solid object, such as a block of wood. After that, students are challenged to identify the composition of a cube by first finding its density. A set of density cubes, including brass, acrylic, and steel, that can be purchased through a school science materials vender are needed. After measuring a cube’s volume and mass to determine its density, that value is compared to density values on a chart that lists a variety of materials. The same can be done with irregularly-shaped samples and the chart if they are denser than water and the displacement method can be used to determine their volume. If they are less dense than water, the students could devise a way to submerge them.
Another lab related to density has to do with forming a column of liquids with different densities. Vegetable oil, water, dish soap, corn syrup, and honey can form a gradient of colorful liquids laying atop each other. Solids, like a cherry or an ice cube, can also be added to the column. After the data is gathered, students are asked why the density of all other substances are compared to the density of water. Lastly, students are asked to explain why oil and water do not mix. They separate primarily because oil and water are immiscible and secondarily because oil is less dense than water. If you shake an oil and water mixture, you first get a dispersion of very tiny oil droplets in the water (or the other way around, depending on which one has a greater quantity), and then the density difference will cause the water to settle at the bottom.
A further lab related to density could be based on a problem that is posed. Students could be asked to determine the thickness of aluminum foil. A chart of density values for common elements would be provided. After being given the density chart and asked to solve the problem, they would need to figure out how to solve it on their own. The students could cut their sample of foil in exact metric length and width dimensions as well as mass the cut sample of foil. After that, they would simply need to solve for thickness using the formula for density. They might also fold or stack multiple layers of foil, measure the thickness, and divide by the number of layers. A comparison of which approach to the problem was most successful would lead to interesting discourse.
Along with this lab student should be given an opportunity to solve problems related to density. Recreating a triangle of mass at the top with density and volume at the base provides students with a mechanism for retrieving three formulas that solve for any of the components.
Phase Changes of Water Lab
This culminating lab provides an opportunity for students to demonstrate their understanding of solids, liquids, gases, and phase changes. Students take measurements of the temperature inside a beaker of ice each minute as it is heated on a hot plate. After collecting their data, students create a heating curve by plotting time versus temperature on a graph. They are then asked which phase changes they observed. During the experiment, students were asked to note when melting started and stopped. So, they are asked where the constantly added heat goes during melting since the graph is flat during that period of time. They should respond that the heat is used to overcome intermolecular forces and enable the phase change to occur. Students are asked where the added heat goes after melting stops and before boiling begins. Likely, they will respond that the liquid is being heated and its temperature is rising. The graph is proof that the temperature of the liquid water is rising because the heating curve is angled upward at that time. Students are also asked whether water and water vapor can exist at the same time and if so at what temperature. They need to explain what is happening during this period of time.