A digital electronics design course I took at the local science museum when I was 11. It was free, so what the heck, I took it on a whim. I didn't know it at the time, but it set the course of my career for the rest of my life even though I'm a software, not electronic, engineer.
for me it was learning devops
Data Smart, by John Foreman. Out of print, but you can get it from Abe Books: https://www.abebooks.com/book-search/title/data-smart-using-...
Why it is cool?
Because instead of R, Gadoop, Spark, Python, whatever... it started explaining data science with excel.
The best part for me was optimization.
A digital electronics design course I took at the local science museum when I was 11. It was free, so what the heck, I took it on a whim. I didn't know it at the time, but it set the course of my career for the rest of my life even though I'm a software, not electronic, engineer.