Why is there no Challenge numbered 1?

Having a semi-mathematical background, I thought it would be nice to think that the next Challenge would be EVEN better! Get it - even numbers - even - all right, I can hear the groan from here! Anyway, I have re-numbered these Challenges twice already, and it is a pain - so hopefully if it becomes important to insert other Challenges into the series, this third attempt using an even-numbering system will allow space for future additions without having to re-number the whole lot again. Here's hoping...

Will this Challenge fill the Whole Two Hours?

Probably not. This is a short Challenge. It may perhaps be possible to complete Challenges 4 & 6 EVENtually (sorry, couldn't resist) during this session as well, if your students are making fast progress. One of the reasons I have kept these first few Challenges short is to try to allow for the type of starting-up problems that seem to happen frequently in programs like this. If everything is going well, you may be able to get ahead - if all hell has broken loose, the short Challenges will at least mean that your students will have been able to have completed something!