Real life examples of 0-indexing It can be perplexing for students to begin counting at 0 when they enter a CS class. I made it a point over and over to talk about "Day 0" and "Week 0" in the opening days and weeks just to build familiarity with the idea. Even so, I sought when explaining this idea to ground it in some real-life/non-CS example where we as humans use 0-indexing naturally and possibly without knowing it. 

Question: where can we find 0-indexing outside of CS and grounded in everyday human experience?

I'll share the one example I can think of below (Q&amp;A style), but I'd love to hear more, potentially better, examples.

[Note: This question relates to another I just posed.]
You can get at this concept very intuitively in strings before you ever get to arrays.  Take a string like "hello world" and ask them a subtle-sounding point: does the string begin here: "*hello world", or here: "h*ello world".  They'll certainly be able to identify the correct answer.

Then ask, "how far from the start of the string do we have to go to get to the 'h'?  Answer in a number of characters. Do we have to move 5 characters away? 3? 1?"  Again, they should be able to identify 0.

Now, it's time for the big reveal.  (My description here is in Java)

"When I want to get at that first character, h, I do it with myString.charAt(0).  Given what we just discussed, why do you think I would use 0, and not 1?"

At this point, they will naturally move to the idea that it is at the beginning, and that we have moved no steps from the beginning.

"Excellent.  This is an example of an index value.  And, in Java, when we do index values, we don't count from '1', we actually count the DISTANCE from the start.  So, if we want the first character, we move no distance.  And how far do we move to get the 3rd character? ..."

When you later get to arrays, you can remind them of the concept, and just say that it is being used again here.