Starting off with C? Ow. R or Python seem like they'd be much better choices for something students would actually use in the future, given their data analysis tools.
If they were CS majors I would entertain them learning the lower-level stuff first but not for what they are trying to accomplish.
You are teaching coding, not computer science and electrical engineering on Day 1.
Setting variables, printing things on the screen, creating loops, making your first functions- Thats day 1.
With that, I would assume most people become addicted to programming, when you make a function, you can feel the power of programming.
After that, I encourage people to solve a problem in their own life. Most of the time, you can rig it in python- but if they wanted to build an app, they are basically ready.
My objective is to give them instant gratification and feed into their personal goals.
Using C is not as bad as it seems. For one thing, embedded projects always start out a lot smaller than software projects on a big computer. You spend a lot of your time as a beginner, understanding the hardware side of things, such as interpreting the numbers associated with i/o pins and other devices. In the entire duration of a beginner course, you might never get past programs of maybe 25 lines.
I use microcontrollers in R&D, and have been quite happy sticking with Arduino based boards.