New Chemistry Tools for LON-CAPA

String Response Problems
Numerical Problems
Image Enhanced Problems

Enhancing LON-CAPA Problems with Images

Images may be used in a variety of ways in LON-CAPA. Any gif or jpg image can be used in a resource or a problem. It can simply serve as an illustration in a resource such as a procedure, as an illustration to explain a problem, or it can be part of the problem as a structure, graph, map, etc. It can be a foil or value in a matching problem, or present data to be used in a numerical problem.

While images can be randomized by selection from a group, one disadvantage comes in developing a scheme for naming the images that does not give the problem answer away. LON-CAPA also uses Gnuplot to dynamically generate images in which random variables can be introduced from a Perl script, avoiding the naming problem, and providing a much greater range of random variation in the image.

LON-CAPA provides an option of randomly labeling components of an image for a matching problem. While the image stays the same, the labeling of its parts is different, and so the matching "value" will be different for different students.

Essentially anything that can be displayed on a web page can be displayed in a LON-CAPA problem. This includes, for chemists, the ability to show molecular structures as rotatable objects to illustrate their three dimensional character. The plug-in Chime can be used for this purpose, but Chime support in the future is questionable and it is being replaced by the Jmol applet. As you will see in a comparative illustration that follows, the Jmol images are crisper and clearer than the Chime images. (The Jmol applet may be slow loading the first time, so be patient). These "3D" images can be used in matching or string response questions. The Jmol.js library can be used to introduce complex interactions with the structure beyond rotating and zooming.

Other Java applets can also be used. Of particular interest to chemists is the ability to have students draw structures as answers to problems. One program for drawing structures on line is the JME Molecular Editor applet developed by and available from Peter Ertl at Novartis. LON-CAPA uses this editor as a way of generating structures that can appear in problems, as well as a way for students to draw structures in answer to a question. The JME Molecular Editor generates a unique Smiles string that is entered as a string for the computer to evaluate. (For some structures, such as meso compounds in the view showing stereochemistry, more than one Smiles string can be generated from one structure. LON-CAPA has a method of evaluating either string as correct.) The University of Southern Maine has posted a nice tutorial on the use of this editor. (Click here to open a JME Editor window. Smiles strings can also be displayed at this web site).

An example of a problem involving a flash simulation is also shown.

To the right are some sample problems illustrating these features. They are presented with a "New Problem Variation" button at the top to allow you to explore the many randomized variations of the problem. Your responses are not recorded, and you have as many attempts as you like.

To view these and additional sample problems as a student in the General Chemistry demonstration course, you must enter a username and password at the LON-CAPA Login page. (First you might want to read instructions at Getting Started with LON-CAPA.) You can get a username and password by contacting Robley Light at Florida State University.


Labeled Gif Structures (Matching Fischer Structures)
Gif Fischer (Assign Configuration)
Chime Structure (Assign Configuration)
Jmol Structure (Assign Configuration)
Jmol (Comparing Two Structures)
Jmol Structure (Comparing with Fischer Structure)
Jmol Structure (Naming Stereoisomer)
JME Editor (Drawing from Jmol Image)
JME Editor (Drawing from Fischer Gif Image)
Gnuplot Dynamic Image (Buffer Titration Problem)
Gnuplot Dynamic Image (Gas Calculation from PV Graph-1)
Gnuplot Dynamic Image (Gas Calculation from PV Graph-2)
Flash Simulation (Titration of a Weak Acid)