Star In A Box version 3
When I was at LCOGT one of the things I helped make was Star In A Box - an interactive tool to explore how stars change during their lives. During the summer it went through some user testing in school classrooms with students in Years 8 (12-13 years olds from sets 1 & 2) and 10 (14-15 years old). The pupils and teachers were asked what they thought was good and what could be improved. We had quite a few positive comments - "cool" and "awesome" were said a few times - and many thought that they learned a lot and had fun. One Year 8 teacher said their pupils were very engaged and still wanted to discuss it at the start of the next lesson! There were also plenty of constructive suggestions and I was asked to use those to make it even better. I've made those changes over the past few months and the new version is now live!
At first glance the box itself hasn't really changed. The one difference you see when you first start it up is that you can select a "mode": normal (Key Stage 3) or advanced (e.g. A-level). This is because Key Stage 3 teachers pointed out that they only used stellar stages such as "Main Sequence" and "Red Giant" but not things like "Asymptotic Giant Branch". They also preferred words like "brightness" rather than "luminosity". You can quickly switch mode at any point by pressing 'm' on your keyboard (or pressing the button on the lid).

Welcome message in Star In A Box CREDIT: Stuart/LCOGT

Previous version of Star In A Box CREDIT: Stuart/LCOGT

New version of Star In A Box CREDIT: Stuart/LCOGT
We've dumped the old "Star Properties" panel as this proved to be a little annoying and confusing. It has been replaced by a simple drop down to change the mass of the star.
The HR diagram has had an overhaul. The text was difficult to read for some especially when answering questions about the temperature and brightness of a star at different times. It doesn't help that the axes are logarithmic. To help with that there is now a crosshair that displays the values on both axes corresponding to where your cursor is. Another thing I did was to make the diagram a little more interactive by letting you jump ahead to any point in the star's life by clicking on the yellow dotted line.

The HR diagram (left: old version, right: new version) CREDIT: Stuart/LCOGT

The temperature panel (left: old version, right: new version) CREDIT: Stuart/LCOGT

The luminosity panel (left: old version, right: new version) CREDIT: Stuart/LCOGT
The time panel/pie chart was a bit confusing to everyone so it has been turned into a stopwatch with functioning buttons! The colours have also been changed so that the main sequence colour matches the main sequence on the HR diagram.

The time panel (left: old version, right: new version) CREDIT: Stuart/LCOGT

Information about your star's life CREDIT: Stuart/LCOGT