Modelling the Expansion of the Universe

When teaching the space portion of this course, there isn't a lot of labs I can do when I compare with the chemistry, biology, or physics teachers.

However, when I do get the chance to do a lab - I'll jump on it.

Here we are, modelling the expansion of the universe with elastics trying to get something similar to Hubble's constant.  Each paperclip represents a galaxy and when you stretch the elastics in between each galaxy, you measure the change in distance from one chosen home galaxy and the others.

Fig 1: I hope they fixed the crooked rulers...

It's a lab that can be done with my grade 9s.  However, the analysis level and connection to the actual expansion of space might not be up to a level that I would like.

I've had some interesting error analysis questions as well as deep questions that strive for true understanding.  (ie:  improvement of measurement in the above picture - ie:  use of tiles? )  What this actually models and how it holds up to current theories about the universe and where it breaks down - all of these are important aspects of the lab that I hope we extract at some point.