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This front-end study was prepared for an October 1997 workshop held at the ASTC annual conference in St. Louis, Chemistry Exhibits That Work.

Molecular Lego Exhibit
Contributed by Mike A. Coles, The Exploratory

Molecular Lego has been a popular exhibit at The Exploratory for many years, but the computer program, developed as a student project, is slow and rather clumsy. The exhibit is to be completely rebuilt.

Visitors using the exhibit were informally interviewed. They were asked their general impressions; if they enjoyed and understood the exhibit; in what ways could the exhibit by improved. In the absence of an interviewer, sheets were left beside the exhibit for completion by the user. Teachers with school groups at the Exploratory were requested to spend some time using Molecular Lego and record their feelings.

Here is a summary of the responses, along with a copy of a sheet for completion in the absence of an interviewer.

Description of Present Exhibit

The aim is to explain the meaning of: atom, molecule, formula, and molecular models.

Importantly, we aim to show that the "space-filling" model constructed is our representation of the basic particle making up the materials around us. A "space-filling" model is constructed from coloured wooden spheres representing atoms (2 carbons, 6 hydrogens, and 1 oxygen). Only single bonds are possible allowing seven compounds to be modelled.

The computer directs the visitor in model construction, explains the atom-counting procedure to devise a molecular formula, and displays possible structural formulae. When the model constructed has been correctly identified, information about the compound can be accessed. The program opens with two choices:

  1. More about Molecules
  2. How to Build a Molecule

If (1) is chosen, a series of screens describes atoms and molecules and focuses on the molecules in water before returning to the opening page. Option (2) lists the balls/atoms available and suggests that one of three depicted models is constructed. Alternatively, the visitor can construct their own model, with the only rule that all the valencies available are used.

The visitor is asked to count the number and type of balls in their model and deduce the molecular formula. A subroutine directs the visitor to check the model and/or counting if an impossible molecular formula is imputed.

The screen displays a rotating graphic of the model to match that constructed by the visitor. Isomerism is possible in one case (ethanol/methoxymethane) so the visitor can identify the molecule they have modelled.

The visitor now has the name, molecular formula, and structural formula of the compound modelled and can select further options:

  • How the compound is made
  • Uses of the compound
  • Facts about the compound
  • Make another molecule

The New Exhibit

Based on the visitor evaluation of the existing exhibit, and our own gut reactions, the exhibit will be rebuilt.

We are keen to keep the basic simplicity of the exhibit, clearly popular with children and the lay public, but we must also cater to the demands of the chemically-illiterate user. These two conflicting issues were apparent in comments from our visitors.

We aim to keep the physical modelling of simple molecules. We feel this hands-on component is important, but extend the bonding possibilities (i.e. multiple bonds) of the available atoms using the program for those visitors with prior knowledge.

We will include a chlorine atom with the presently used carbon, hydrogen, and oxygen atoms to extend the range of compounds that can be built. The atoms will be constructed from plastic spheres with an improved linking mechanism for greater robustness. Model construction will still be easy, but 17 compounds can be modelled, allowing the visitor greater independence and dramatically increasing the range of chemical properties illustrated. A number of the compounds are unfamiliar, some have strange properties and some decompose violently. The decomposition of one into a more stable multiple-bonded species will allow entry to a subroutine investigating multiple bonds and the relative stability of compounds from bond enthalpy data.

Many of the compounds illustrate isomerism, including optical isomerism, and these can be used as an entry into a subroutine investigating this important area.

Supporting Computer Program

Improved technology will allow faster operation and high quality molecular graphics. For young visitors, an option involving simple text, graphics, and maybe a cartoon character, will be investigated. The inclusion of a soundtrack to support the written text could ease the journey through the program. The database of compound information to be accessed when the molecule has been identified will include graphics, pictures, and maybe film sequences. It will be arranged in a hierarchy of complexity, starting with the very simple and developing towards the complex for the chemically literate. The visitor can "drop-out" when their interest wanes. Many of the repetitive loops in the program, which were mentioned by the visitors questioned, will be refined.

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Comments on Molecular Lego
Staff and Visitors


Detail on current plore and hardware

  • The balls fell apart a little easily.
  • Speed up the display -- it takes too long to move through the screens
  • Miss out the question about "Are any atoms missing?"
  • The exhibit is often used socially -- say by a parent and child. Re-design the table to give room for two seats and make it lower and round.
  • Perhaps plastic molecules would be more durable (the wood ones get chipped and lose paint when dropped, which is often), also having the molecule symbol written on each molecule e.g. 'O' or 'C' would simplify things.
  • The molecules need to be connected better so they don't keep falling apart.
  • I like this exhibit, the only thing wrong with it is you could label the lego pieces and have them made out of plastic to be brighter. Excellent.
  • Get a faster running computer.

General

  • Basically, I think this is a clever activity to stimulate thought about molecular composition.
  • Nice idea to combine physical object with computer activity
  • More variety.
  • Very good, but a bit boring after awhile.
  • Please improve! I don't understand it.
  • Don't wreck this simple exhibit by making it too difficult.
  • Brilliant. Super!
  • Get something more interesting.
  • Get some really nice stuff.

Presentation of information

  • Some of the words on the computer are long for children.
  • Structure the information about the molecules built, by complexity, rather than topic - put the easy stuff first and let the visitor decide how much they want of the "turgid" stuff.
  • Some of the information given about compounds is vague. e.g. Methane - uses - "Important raw material in the chemical industry"
  • I think the text is lost on the younger children and they are the ones who enjoy building the models. Could the text be on 2 levels, one being more simple and pictorial?
  • The explanation of what a molecule is at the beginning is an option and could be missed. I think this should be the introduction and not a choice otherwise at the end you still don't know what a molecule is.
  • The fact/uses/how it's made sections could be more appealing with some illustrations.

User interface

  • Might be nice to let the user investigate how many different combinations they can produce (rather than the computer prompting you to build one of 3 molecules) initially.
  • Would a 'touch & drag' screen be possible (while retaining the hands-on model) for building molecules?
  • Simplify the count process for the second time of use.
  • Make the program more friendly for children by having cartoon characters introduce the task.
  • Needs to be fun, maybe a little man telling the information.
  • Add sound to the screens for a commentary.

Extensions

  • Extend the current program with a more advanced program as well as the present one. If this included a double carbon bond and one or two additional elements, it would be possible to demonstrate geometric isomerism and optical isomerism. The screen could show mirror images for the latter.
  • Add one extra atom -e.g. a chlorine, to increase the range of molecules possible and give optical isomers.
  • Add one other carbon and another atom -- e.g. a halogen -- so that we can make more molecules.
  • Show more complex molecules such as DNA.
  • Add the chance to use double and triple bonds -- it's a shame not to be able to make common simple molecules like carbon dioxide.
  • Theh addition of one or two carbon atoms would allow homologous series to be investigated, together with their properties; e.g. alkanes, alkenes, alkynes, alcohols, and ketones up to C4.
  • Quite an interesting introduction -- it would be helpful to be able to remove the "stems" so smaller molecules can be made.
  • What about including nitrogen?
  • Something about polymers.
  • Structures of sugars -- monosaccharides plus celluose vs. starch.
  • I think it would be good if you had more molecular lego so you could explore more molecules.
  • Simple explanation of more complicated molecules would be a good idea.
  • What is the molecular structure of yeast extract?

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Comment Sheet for Molecular Lego
Molecular Lego (the plore about making molecules from atoms which uses wooden balls and a computer display) is to be rebuilt. We would like to improve it. If you have any comments about how it works now, how it should be extended or changed, please write a note on here. We are more interested in how it should work with visitors and what it should cover than how the program works technically.

Some comments so far:
(sampling of comments from above were placed here)

Your comments:

 

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