UniServe Science News Volume 12 March 1999


Chemical Structure Drawing and Marking on the Web

Damon Ridley
The University of Sydney
Dave Proctor
Hampden Data Services

This article is reprinted, with permission, from the Proceedings of The University of Sydney Chemistry IT Workshop: Towards Web Teaching, November, 1998.


Current tutorial programs in web-based teaching and learning are limited to text inputs. Thus, in the field of chemistry, while questions may be asked in text or graphic formats, answers may be text only. This has severe limitations in tutorials (particularly in organic chemistry) where the only effective way to teach and to learn is through chemical structure diagrams.

As there are many ways in which a single chemical structure may be correctly drawn, it would be totally impractical to create a library of correct structures against which student structures are to be matched. Accordingly, we have developed ChemMark-WWW, a chemical structure drawing and recognition web interface which enables chemical structures to be drawn and marked. The program automatically creates a structure connection table for the answer given by the student and matches it against the structure connection table for the answer provided by the instructor. Answers can be post-processed so that the student gets immediate feedback, and the lecturer can immediately see what marks have been awarded - and can also see exactly what the student did!

While it is a simple matter for teachers to insert their own questions into the program, the first release of ChemMark-WWW will have a number of already prepared tutorial questions. The questions cover the usual materials presented in First Year Organic Chemistry courses.


The student logs into the server on which the program has been loaded, and enters his/her name and password (Figure 1).

Figure 1.

Figure 1. The introductory page, which is accessed from a local server through the web. The 'Tutorial' option enables marks to be recorded; the 'Practice' option is for students to practice other examples first. Student name and password must be inserted.

A screen with the different tutorials is then shown (Figure 2). In its present form, each tutorial has between 10 and 20 individual questions.

Figure 2.

Figure 2. Currently eleven tutorials have been prepared and will be part of the initial release. However, it is a relatively simple matter for the teacher to prepare additional tutorials. The student clicks on the tutorial to be answered.

A typical example begins in Figure 3. Each tutorial has a preamble through which the student reads and which gives a summary of the chemistry to be learnt/tested in the tutorial. At the bottom of this page the individual questions are listed and the student clicks on the question to be attempted. (Note that marks are progressively awarded and in this case (Figure 3) the student did not get Question 1 correct, but was correct in the answer for Question 10.)

Figure 3.

Figure 3. Each tutorial has an introductory section that outlines the general chemistry in the tutorial. The specific questions are then listed. The student clicks on the specific question to be answered.

As an example, Question 5 is now clicked and the question is presented, in this case in graphic format (Figure 4).

Figure 4.

Figure 4. An example of a question presented with a structure diagram. The student clicks on 'Draw Query' and the structure drawing program appears.

The student then draws the answer using a simple structure drawing program and the answer is submitted (Figure 5).

Figure 5.

Figure 5. After the structure has been drawn the student clicks the 'Back' button and the question and answer now appear. The student clicks 'Submit Answer' and the attempt is marked.

If the answer given is correct, two marks are awarded and the correct answer, and comments, are displayed (Figure 6).

Figure 6.

Figure 6. The student then is told whether the answer was correct. If incorrect, the student is asked to retry. Eventually the correct answer, with teaching comments, is presented.

If the answer given is not correct, the student is told and is prompted to try again. If the second attempt is correct, one mark is awarded; if incorrect, no marks are awarded. In each case the correct answer and comments are displayed.

Logging of marks

The teacher may independently enter ChemMark-WWW, and display summaries of marks awarded. Marks are collated per student and per tutorial (Figure 7).

Figure 7.

Figure 7. The teacher has immediate access to student marks. Marks are presented per student and per tutorial. Marks are linked to actual answers presented by the student so the teacher can identify specific problems.

All the boxes are linked to the students' answers, so by clicking a box the teacher can immediately see what the student has done (Figure 8).

Figure 8.

Figure 8. An example of student answers to which the teacher has access.

General comments

ChemMark-WWW currently is restricted to structure input only, but stereochemical issues and reactive intermediates can be accommodated. For example, it is possible to ask a question: "Draw the structure of the intermediate formed when propene is treated with HCl". Here the carbocation required is easily recognised by the program.

ChemMark-WWW allows for multiple answers to be drawn on the one page. Thus, in answer to a question: "Draw the structure(s) of the products formed when toluene is treated with a mixture of nitric and sulfuric acids", the ortho- and para- products can be drawn in the one diagram. ChemMark-WWW also allows for alternative answers. For example, in answer to a question: "Draw the structure of the alkyl iodide and the carbonyl compound that could be used for the preparation of methylenecyclohexane", either of the alternatives (formaldehyde/cyclohexyl iodide or cyclohexanone/methyl iodide) are accepted.

On the other hand, ChemMark-WWW does not handle the "arrow notation", where in any case organic chemists have slightly different interpretations of what is "correct".

While a number of questions will be available in the first release of ChemMark-WWW, it is a relatively easy task for the teacher to present specific tutorials. Text is entered into a simple word-processor program (for example, Notepad), and questions and answers that involve structures are prepared with the same structure drawing program used within ChemMark-WWW. ChemMark-WWW may be used at all levels in the teaching of organic chemistry and, where mechanistic aspects are required it is a simple matter to present questions that address the structures of the key intermediates.

ChemMark-WWW was alpha tested with a group of students in Chemistry 1 from The University of Sydney in September/October, 1998. Students learnt the structure drawing program in about 20 minutes. They found the program provided a very exciting and informative way of learning organic chemistry. They liked the immediate feedback on their own answers, and the general comments. They listed a number of features and benefits (Table 1).

Access through the webEase of access
Practice problemsStudent works at own pace and develops skills
Marked problemsComputer marked structures overcomes need for labour intensive hand marking
Structure or text input of questionsVersatility; correlates with traditional options for presentation of questions
Introductory comments to tutorialsFacilitates teaching/learning
Easy-to-learn structure drawingSaves time
Structure input of answersWorks on structure connection tables so accommodates all structure symbols and different structure presentation formats
Reaction intermediates and stereochemistryAllows testing of mechanisms
Library of questionsRepetition helps learning
Specific questions easy to prepareMinimal learning of program required
Available in any languageAllows teaching in all countries
Student and correct answers presentedImmediate feedback for students
Comments on answersFacilitates teaching/learning
Marks processed automatically and available electronicallySaves time for teacher

Table 1. Features and benefits of ChemMark-WWW

ChemMark-WWW is produced by Hampden Data Services, UK, in conjunction with The School of Chemistry at The University of Sydney. It will be available commercially, in Windows and Mac formats, early in 1999.

Damon Ridley
School of Chemistry
The University of Sydney


Dave Proctor
Hampden Data Services
United Kingdom

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UniServe Science News Volume 12 March 1999

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