Middle school science is a critical preparatory program for high school science education. Teaching 8th grade science is a component of the foundation for high school biology, chemistry and physics which are essentially college preparatory courses. The ____Insert district name info here____ Independent School District considers science in the 8th grade to have measured core competencies of problem solving with unit conversion, understanding and applying the scientific method, and demonstrating an understanding of scientific discover through laboratory experiments. Science in the 8th grade within this district is taught in a lecture classroom adjacent to a laboratory with benches and equipment. The curriculum covers primarily the hard physical sciences of chemistry and physics with associated laboratory experiments and experimental write ups. Students are expected to focus on application of concepts that apply concrete, but difficult-to-visualize ideas to experiments so that the principles covered within these topics are discovered to be verifiable by the scientific method.
Chemistry is among the most powerful of the scientific disciplines in terms of the impact on life and culture. Chemicals surround society from the main-stream media attention paid to toxins in the environment and water supply to the healthcare benefits of pharmaceuticals to the performance of polymers in structural materials. The science of chemistry requires both a fundamental understanding of certain "basic" concepts and a capability of applying those concepts in continuously developing new situations as a student learns new topics in the syllabus. One basic concept that carries through chemistry and other scientific disciplines deals with the concept of gas laws. Gas laws are fundamental physical chemistry equations that explain the interaction of the physical state of matter known as a gas and relate the following:
The pressure that a gas exerts on its container
The volume that a gas takes at a given pressure and temperature
The known quantity of gas in mass or number of molecules
Although these relationships may appear trivial, the laws that govern them in the physical world apply to every science from biology with respiration to engineering in submarines to atmospheric science with weather. The following literature review will address whether or not the concept of demonstrations aids in the understanding of gas laws for 8th grade science student as they enter into high school chemistry.
Part B: Literature Review
High school chemistry concepts have a basis in the comfort of a student's exposure to scientific method and the rationalization that a topic can be tested to verify a hypothesis. A significant component of high school chemistry and college general chemistry focuses on gas laws which govern the relationships between volume, temperature, pressure and mass of a gas. The concept is often introduced as a system of equations relating these properties to an ideal gas. This concept captures the student for which mathematical concepts are taught in an abstract concept but can leave more visual and empirical learners quickly left behind. Three methods of teaching gas laws through demonstration are reviewed below with a critical evaluation of the method of teaching, followed by a review of the status of assessment in teaching chemistry to early introductory science students.
Students have conceptions about gases and the physical properties of gases and the matter that composes them. Testing indicates that students often believe that gases weigh less than solids or liquids and that water decomposes when boiled (Mayer, 2011). The education topic tested observed introductory science students targeting the basic understanding of gases related to the transition from liquid to gas, volume, and weight. Students were provided a test that asked a set of 10 basic questions to assess the understanding of the relationship between volume, weight, and the state of matter. The results of the test indicated that the most common misconceptions were that the mass of matter decreases when a liquid changes to a gas during boiling, and that this change of matter is a destructive process. Without offering correction to the students after the examination, the educator presented a demonstration with a hypothesis that tested:
1) The weight of a closed system where a mass of water was boiled and the vapor was contained and allowed to expand to see if the mass was conserved
2) The volume of water after condensation
The demonstration presented students with a fixed volume of water that was boiled and allowed to expand into a balloon. The data showed that the mass did not change through the system if the gas was retained although a substantial apparent change in volume was noted. Cooling of the system reverted the volume of gas into the boiling vessel and the volume of water was noted to be conserved as liquid water. A subsequent repeat of the test resulted in a substantial increase in correct responses for the understanding of gas mass and phase changes.
The difficulty encountered in students mastering an understanding of gas relationships is often assumed to be limitations on algebra skills. The gas equations rely on simple substitutions of algebra in multiplication and division (Robins 2009). The assumption that algebra skills were the lynchpin for the understanding of gas laws was tested by assessing student's competency in algebra. There was no subsequent correlation between algebra skills and understanding of gas laws and substitutions in those laws. Subsequent testing in the relationship of both units and unit substitution and the physical concept of gas volume as shown by demonstration and experimental evaluation resulted in improved competency on tests of gas law understanding.
General gas law concepts can be taught to introductory science students with the most rudimentary of materials and equipment and these demonstrations can have profound impact on their understanding of the concepts that underpin the gas laws themselves. Empty plastic water bottles can be used to show dramatic changes that occur for gases with changes in temperature (Campbell 2011). Students are taught that the volume of a gas changes with temperature and that if the temperature of a gas within an open container is increased, the number of molecules within that container decreases as the heated molecules escape. Capping the container and allowing it to cool can show changes in the container volume. Students were presented with 1/2 liter plastic water bottles, chemical hand warmers and a hypothesis regarding the effect of temperature on the gas within the bottle. Warming the air within the bottle and then capping it demonstrated a violent change in the volume as the bottle collapsed upon cooling. Students were able to explain the concept of the effect of temperature on a gas and the number of molecules after the demonstration.
A difficulty in the understanding of any applied science demonstration is the application of assessment in determining if the demonstration or experiment is teaching the students what the concept is and if the way that concept is taught can be accurately measured. Chemistry and demonstrations used in this basic science are not exempt from the need for assessment and the invoking of a physical experiment should have a core of a desired outcome based on a topic in chemical education or the exercise is a waste of time (Bretz 2012). Assessment tools should observe first the desire to understand how the students grasp of a concept will be measured followed by what an educator wants them to know. If the concept is gas laws or relationships between gases and their physical properties one should design the curriculum to be able to answer how the students will be assessed and then input the experiments, examples, lecture and problems to provide an outcome that can be assessed.
Part C Action Plan for Implementation in Classroom
The introduction of gas physical properties and their relationships to introductory science students has been improved…