What are some resources to test your data science skills?
If you want to move from theory to application then I suggest to do exactly that: get your handy "dirty"!

UCI Machine Learning Repository has some easier datasets to get started. Kaggle is great too but before going for any competition look for an easier dataset from their repository. 

If you prefer something with more guidance the book "Introduction to
Machine Learning with Python" by Mueller and Guido contains many examples starting with the classic Iris dataset. 

Finally, you could consider an online course. The Udacity Nanodegrees include projects which you need to submit so it gives some basic hands-on experience. Though, in your specific case, I would only go this route if you think it might help your CV.