DISCIPLINE
Chemistry

DURATION
One learning session (e.g. small period of contiguous time in a lecture or tutorial, one week of the subject/unit/course).

However, to be effective, the learning design should be repeated a number of times, in a number of contexts, throughout the duration of a subject; that is, whenever a connection between the lab-, molecular-, and symbolic-levels is useful to understand a concept. For example, first when explaining acid dissociation, then later when explaining the difference between acid concentration and acid strength.

ICT USED
The VisChem animations are available in CD, Web-deliverable and videotape formats, as commercial products, supplements to textbooks, and freely-accessible web sites.

Some sources are listed below.

• The resource CD containing all 82 animations in cross-platform QuickTime format (288Mb), cited as:
  Tasker R, Bucat R, Sleet R, Chia W, Corrigan D (1997) VisChem Resources — Learning Chemistry Through Visualisation of the Molecular Level.
• A series of three videos, with lecturer’s notes and student activities, depicting chemical substances and reactions typically covered in an introductory chemistry course, cited as:
  Tasker R, Bucat R, Sleet R, Chia W, Corrigan D (1996, 1997) The Molecular World of Water (13 min)
• The Molecular World of Reactions in Water
  Part 1: Dissolving, Precipitation and Complexation (25 min)
  and
  Part 2: Ionic Equilibrium, Acid/Base and Oxidation/Reduction Chemistry (33 min)
  

DELIVERY CONTEXT
The learning design is currently implemented in a face-to-face lecture environment, with students able to work in pairs and with the support of an experienced lecturer to maintain focus on key features, and facilitate discussion. The passive, transmissive nature of this mode of delivery is still the most common in first-year chemistry, but not ideal. However, the evaluation study we conducted was limited to this learning context.

The interactive software resources cited above use the VisChem animations in interactive interfaces. However, the all-important ‘constructivist’ approach of the learning design has not been implemented in these resources. Evaluation of their effectiveness for learning has not yet been done.
Interactive online delivery of the learning design will be possible when a molecular construction tool, that provides feedback on a student’s model before s/he sees the VisChem representation, can be produced.

TARGET AUDIENCE
Generally, this learning design is targeted at first-year undergraduates in science-based courses, but it has also been used extensively with upper-secondary level (years 11 and 12) HSC Chemistry students. Ideally the approach should be used in middle-school science classes where the fundamental ideas (and misconceptions) in chemistry are first introduced.

A specific profile of a student cohort involved in our research study using VisChem resources is as follows:

“Of the 48 students that we have comprehensive information on, 32 had previously completed chemistry at HSC level (2U Chemistry, 3U Science or equivalent), 11 had not studied beyond junior (year 9/10) chemistry, two had studied year 11 chemistry only, one had not studied chemistry for many years, and one had an unknown background.”

In general, these students would be at the weaker end of the academic-ability spectrum of first-year chemistry students in Australia. However, the VisChem animations are available on the CD supplement to Atkins & Jones, Chemistry: Molecules, Matter, and Change, 4th ed. used by first-year students at the University of Technology, Sydney; the University of Wollongong; the University of Adelaide; Flinders University; and Edith Cowan University.

The critical point is that our research has shown that unless students are convinced that developing accurate mental models of the molecular world will help them to get higher marks in the subject’s assessment, they will not engage with the learning design in a thoughtful way. This is particularly true with high-achievers with a surface approach to learning.

This condition does require the subject coordinator to assess the accuracy of student mental models of the molecular level. This is a challenge because students can often perform well in conventional exam questions where only rote-learning and an algorithmic problem-solving approach is needed

COHORT
The nature of the learning design is that there is no limitation on the number of students involved. In our evaluation study, the activity involved 90 students in a lecture-theatre setting, of which only 48 students were studied in detail.

The most important criterion is that the student can obtain feedback on his/her molecular-level representation before seeing the VisChem animation. This is essential in order to focus attention on the key features of the representation. This feedback can be provided by one or more peers, a lecturer, or from an ICT resource.

BROADER CONTEXT
A deep understanding of chemistry requires well-developed mental models of the structures and processes that occur in the molecular world. The VisChem resources are designed to help students develop useful models that they can apply to fundamental concepts in first year, and complex chemistry concepts in later years.

For example, in second and third year, animations are shown in advanced contexts to draw out new features to explain advanced concepts. Furthermore, as students refine their molecular-level models they can begin to see the limitations of the animations in portraying some advanced features of the molecular world.

We see this approach as most appropriate when introducing students to the structure and bonding in common substances, and to common types of reaction, some examples of topics where this learning design could be useful later on are:

1. Concentration of ions in solution (Note: VisChem animations of solutions are designed to portray 1M concentrations).
2. Thermochemical cycles (e.g. the competition between lattice enthalpy and hydration enthalpy in dissolution of an ionic salt).
3. Nature of solute/solvent interactions in colligative properties.
4. Importance of solvent and temperature in reaction mechanisms.
5. Effects of changes on reactions at equilibrium.
6. Difference between acid strength and acid concentration.

Overall intended outcomes are to assist students to:

• Build scientifically-acceptable mental models of substances and reactions at the molecular level.
• Relate these models to the laboratory level and symbolic level in chemistry.
• Apply their models to new substances and reactions.
• Use their models to understand Chemistry concepts that require a molecular-level perspective.
• Address common misconceptions (identified in the research literature).
• Improve their confidence in explaining phenomena at the molecular level.
• Enhance their enjoyment of chemistry by providing ways for them to use their imagination to explain phenomena, instead of just rote-learning and algorithmic problem solving.

Specific learning outcomes are designed to assist students to:

• Focus their attention on key features of their prior mental models of substances and reactions at the molecular level.
• Enrich, develop or amend their mental models to account for laboratory-level observations.
• Link their mental models to the chemical symbolism used in chemistry.

IMPLEMENTATION OF ASSESSMENT STRATEGIES
Assessment of the molecular-level visualisation skills developed in this design is essential to convince students the effort is worthwhile.

Students are required to use the three-thinking-level approach, and draw molecular-level representations, in lab classes and in their reports for assessment.

Some exam questions explicitly require drawing molecular-level representations. An example of a question and an acceptable solution are shown below:

A sample answer:

The key features required are those pointed out in the relevant VisChem animations:

• Ions and ammonia molecules present in the correct ratio.
• The ions and ammonia molecules are hydrated and separated.
• The water molecules around each ion and ammonia molecule are oriented with either H-ends or O-ends pointing at the ion or molecule, depending on its charge.
• There are many more water molecules than ions and ammonia molecules.

IMPORTANCE OF ASSESSMENT STRATEGIES USED
One reason student misconceptions about the molecular level are not detected at university is that questions rarely probe this level of understanding explicitly. An example of a question style, like the one above, that does probe this level was recognised as novel and effective by its inclusion in the nationally-published assessment guide for tertiary educators - Assessing Learning in Universities (Nightingale, Te Wiata, Toohey, Ryan, & Hughes, 1996).

Student drawings and descriptions of their conceptions of structures and processes at the molecular level often reveal misconceptions not detectable in conventional equation-writing questions. Activity 3 in the learning design provides the opportunity for students to identify these misconceptions in their own representation, or those of their peers. Experience suggests this is more effective than having the lecturer simply listing common misconceptions.

Reference:

Nightingale, P., Te Wiata, I., Toohey, S., Ryan, G., & Hughes, C. (1996). Assessing Learning in Universities. UNSW Press, Sydney.

WHY ICT IS USED
Due to a shortage of high quality resources that portray the molecular level, most chemistry teaching only occurs at the laboratory and symbolic levels, in the hope that the students’ mental models of the molecular world will ‘develop naturally’. Students are left to construct these models from the static, often oversimplified two-dimensional diagrams in textbooks, or static, often confusing ball-and-stick models, or their own imagination.

The initial use of ICT was to produce and present the VisChem animations in a constructivist teaching strategy, whilst requiring a skilled educator to guide the process.

HOW ICT USE HELPS
ICT allows a drawing/evaluation tool to be developed to elicit a student’s prior understanding of the molecular level, and the VisChem animations can be embedded within an interactive multimedia interface. ICT offers the opportunity to implement this learning design in a flexible-learning mode.

MOST IMPORTANT ICT CONTRIBUTION TO LEARNING DESIGN
ICT allows development of a drawing/evaluaton tool to enable students to practice producing molecular-level representations, and obtain specific feedback on these, and then to compare them with VisChem animations, without requiring input by a lecturer. This is essential in large first-year classes.