eXpresser v0-1081

Release 0-1081 is now available. It includes full expression parsing so that the user can now specify expressions such as 5*red + 3. Unnecessary brackets are automatically removed at present.

eXpresser v0-1053

The latest version of the system (v0-1053) now includes a mock-up of ‘resource allocation’. Each colour now has a numeric limit. By default this is 10 per colour. Once this number of basic blocks of that colour have been used up, blocks are no longer painted using that colour but instead are shown with a thick red border since the resource has ‘run out’.

The aim here is for the user to see value in analysing their constructions as they construct them not after they construct them. Ultimately, in the case of the footpath pattern for example, we want the user to be able to say that the number of green needed is 5 times the number of red plus 3. Rather than seeing this as a secondary phase, resource allocation is a mechanism for integrating both analysis and construction (as discussed in previous meetings and in Issue 237.)

At any time, users can use ‘color icon variables’ in the same way as ‘iterations’ icon variables. The expression toolbar has been updated to include an extra button ‘color’ which provides this functionality. A lot more work needs to be done here.

Currently there is nothing to stop the user just allocating (say) 10,000 to each colour and working without worrying about the algebra. We have yet to design and implement mechanisms for what happens if the user has too many resources.

Note that there are some bugs with repainting but it generally works well enough to function as an object to think with. Note also that currently expressions can only consist of a single operator optionally repeated. For example, 3 + 5 + 2 is fine as is 4 * 3 * 2 but 3 * 4 + 2 is not parseable yet. This means that the expression 5n + 3 is not parseable yet either. This will be addressed in the near future.

ICALT08 Presentation

I just presented the MiGen project at the ICALT 08 conference. We were accepted as a short paper so I had 15 minutes for the presentation and 5 minutes for questions. I gave a very brief overview of the project, introducing the three main components eXpresser, eGeneraliser and eCollaborator. I then showed ShapeBuilder and demonstrated the pond tiling task, introducing the idea of messing up. I then explained how we moved away from shape-based problems since this doesn’t cover many typical generalisation tasks in the National Curriculum. I then showed the latest version of the system that I had (v0-1004). I demonstrated basic shapes and creating a diagonal and then demonstrated the ‘footpath’ problem, showing the backward-c construction and the 2n+1 construction. (Note that this uses the new expression parsing facilities in 0-1004).

I was asked two questions at the end. The first was about whether the system was really teaching algebra. I agreed that it was only teaching part of it; for example, it does not help with the idea of doing the same thing to both sides of an equation. I emphasised that the system was about mathematical generalisation and that algebra is a useful tool for this. Admittedly the paper title includes the word ‘algebra’ so perhaps this is slightly misleading. The second question was about possibly displaying (essentially) a table of numbers so that the child can abstract the pattern. I explained that this was precisely what we were trying to avoid since suhc premature engagement with numbers is problematic in general. Also, table-based exploration is not scalable for problems of more than one variable (for example).

Another comment was also made saying that the system could automatically show how changing iterations (say) would make their pattern look more and more messed up. For example, imagine that their pattern is hard-wired to look okay for 5 iterations. If the user changes this to 6, it looks messed up but if system then changed it progressively to 7, 8, 9, etc the user would see that their construction getting more and more messed up.

Various people (after the session) felt that the system could be useful for age ranges far above our 11-14 age range.

eXpresser v0-991

A last minute change to some icons in the software in advance of tomorrow’s user sessions has led to a new release, v0-991. This has professional-looking icons for icon-variables now using the cog () and arrow images ( and )  from: http://i.hbtronix.de/.

eXpresser v0-990

The latest release of the system is now version 0-990. Here is a brief description of the updated and new features:

• The slow-down experienced in earlier versions is not so noticeable. This is due to the fact that patterns really are made out of constituent shapes now rather than spoofing them.
• Configuration files can be specified. The default config filename is ‘config.txt’ and this should be located in the same directory as the jar. If you want to use a different config filename, you can specify it on the command-line via a shortcut.
• Logging is now in place.
• The default colour for initial blocks is now green (!)

The observant amongst you may notice that this is a siginificant numeric jump from 0.27. This is not indicative of changes of this magnitude, however. Instead, it is due to the fact that we have changed our release naming convention. So release 0-990 is in fact subversion revision 990 of our repository. The prefix ‘0′ means that it is pre-release. i.e. not 1.XX. Notice the hyphen instead of a decimal point.