Doing homework in learning environments: Virtual Lab

Our most well-developed applet to date is a Virtual Lab which handles all of the aqueous reaction types and thermodynamics commonly covered in introductory chemistry ( http://ir.chem.cmu.edu/irProject/applets/virtuallab/ ). Users can select from hundreds of standard chemical reagents and mix them together in any way they see fit using equipment and procedures commonly available in introductory laboratories.   This software differs from the previously described applets in that it is both general and flexible, so that it can be easily incorporated into existing courses at diverse institutions and may be used to meet diverse goals.  For example, some instructors may want to focus on reducing students' difficulty in making connections between theoretical concepts about the molecular level and observations at the macroscopic level, especially when both the concepts are observations are unfamiliar to the students. In those cases, providing practice with a simulation can increase familiarity with some observations and begin to bridge the gap to theory.  Some instructors may want to convey a greater intuition about chemical processes and wish to communicate more clearly the abstractions that are not immediately obvious from either manipulating chemicals in a physical laboratory or solving mathematical equations. Our hypothesis with the Virtual Lab applet is that we can speed the communication of this vision by providing students with a flexible environment where they can interact freely with chemicals and see directly how their actions modify the chemical species in solution.

One key feature for teaching complex concepts seems to be providing multiple representations so that students can flexibly encode and use what they have learned.^[10] Our software shows both a bench-top view of the experiment as well as a graphical representation of the species in solution so that students can immediately see the molecular-level changes in a reaction. The additional representations of the species in solution provide a small amount of scaffolding to enable students to detect errors when they occur, but otherwise the student’s observations and feedback in this computer-based context are reasonably similar to a real laboratory experience. This type of technological support can facilitate students’ perception of critical features to be learned.^[13] We are about to begin careful observations of student interactions with the software to see how effectively they are able to interpret this feedback in light of their hypotheses, since some research has shown that this connection can be difficult to make.

A primary goal of the applet was to create a student-centered educational environment in which students are given more meaningful goals and allowed a greater flexibility in achieving these goals.   Because our simulation environment opens up a wider range of goals than paper-and-pencil tasks, alternative types of assignments can engage students’ curiosity, provide a challenge, and allow students to make choices about the procedures they use.^[11]  For instance, the standard problem type of “A was mixed with B, calculate the outcome” can be transformed into “You want this outcome, what do you do to get it?”. The latter resembles more authentic activities performed by chemists.  Such goals have been suggested as a means to promote intrinsic motivation, and have the potential to increase students' time exploring chemical concepts and interest in pursuing the field as a career.

The Virtual Lab display is divided into the following three panels:

Stockroom Explorer This provides access to the chemistry stockroom. 

Workbench This allows the user to perform chemical manipulations on the solutions. You can switch between workbenches by clicking on the tabs.

Solution Info Panel This panel displays information about the workbench’s currently selected solution. The text lists the concentrations of the species in solution, in moles/liter. The bar chart shows the log₁₀ of these concentrations. The lowest panel is a pH meter.

Double-click a solution in the Stockroom bring it onto the workbench. To transfer liquid between flasks, drag the source flask onto the recipient flask. (The mouse pointer must be on top of the recipient flask, such that the recipient flask becomes highlighted.) The source flask should appear rotated and above the recipient flask. You can now type the number of ml to transfer into the text box at the bottom of the screen and hit return or the pour button. Extra glassware can be retrieved using the buttons on the left of the workbench. See the user guide for more details on how to use the laboratory simulation (http:  link to the front page of the vlab for now, since a link will be placed there).

Uses in Lecture

Instructors can use the Virtual Lab in lecture to demonstrate phenomena such as titration curves and to promote a more intuitive understanding of pH and buffer zones.  The Solution Viewer provides graphical reinforcement of the changing concentration of species in solution, while a pH meter enables students to follow the rate of change of pH with slow addition of base in a titration.  While the lecturer must carefully narrate what feature to observe as the titration progresses, the multiple representations available to students may encourage deeper understanding of acid-base chemistry. 

Uses Outside the Classroom

The Virtual Lab's design has as a core precept that what students practice is largely what they learn and retain.^[12]  A simple initial use of the Virtual Lab is to encourage students to check their understanding of textbook-style homework. Because they can check partial solutions to problems, many students will be able to avoid the frustration that comes with pursuing incorrect paths and to avoid reinforcing misconceptions by repeating them. A homework assignment, used this semester, that implemented this approach with regards to acid base chemistry can be found at http://ir.chem.cmu.edu/chem106/assignments/hw5.pdf .

We also intend this software as a tool to enable faculty to create a variety of assignments  that promote stronger connections between chemical processes and pencil-and-paper calculations.  Our approach is similar to other technology-enhanced student-centered learning environments[13] which seek to actively engage students in constructing connections between new knowledge and existing conceptions and immerse them in concrete experiences to anchor their understanding, while also allowing the student freedom to explore.  For example, some of these assignments may focus on practicing, planning and implementing, in a simulation environment, some procedures similar to what they would do as preparation for traditional laboratories.  Some may focus on a “design” goal such as creating a buffer that would withstand the addition of a particular volume of acid.  Others might be to design an experiment to address a particular question.

Consider, for instance, a student using the simulator to experiment with strong acids and bases. When a student adds NaOH to water, they will see immediately via a bar graph that it exists in solution as Na⁺ and OH^-. They can then see that the primary effect of adding HCl is to consume some of the OH^-. Our hypothesis is that this interaction will give them a more intuitive feel for the reactions of strong acids and bases than could be imparted by listening to descriptions of the phenomenon in lecture or solving the related paper and pencil problems. Such visualizations become even more powerful when applied to more complicated phenomena such as the behavior of buffers.

A simple assignment, where students use the virtual lab to measure the binding constants between nucleic acids,  can be found at http://ir.chem.cmu.edu/chem106/assignments/bonus1.pdf .  A more challenging assignment, in which students must first characterize a weak-acid dye and the binding of this dye to DNA and then construct a buffer to achieve a certain percent binding, is located at http://ir.chem.cmu.edu/chem106/assignments/hw-bonus2.pdf .

Future changes