It depends on the individual. I spent the majority of my early teens disassembling binaries and writing programs to patch software, reading virus source code and trying to wrap my head around polymorphic viruses, manipulating acid/base/oil to make soap and metals to produce gas and currents and observe surface phenomena, distilling plants and flowers to make oils, trying to understand programs to simulate forces on an airplane, lockpicking, perfecting copper tube-lead-match firecrackers, making darts that fly go relly far. Super, super fun, right? My nephews and nieces wouldn't do that if I paid them. This is mainly due to the fact that I don't know how to teach them and I didn't invest time in learning how to connect with younger people.

I'm watching this thread for ideas. I'm considering "Physics for Everyone" by Landau and Scratch for which I have an apprehension because why learn that when I know they're capable of learning to code directly, but maybe it would help getting them hooked.

Although not exactly a structured course or lessons, FEATool has been designed to be a very easy to use toolbox for physics simulations and learning by experimentation and trial and error with built-in tutorials (currently free license for home use during the lockdowns [1]), for fluid flow and heat transfer the simpler CFDTool might be more appropriate with an even simpler interface that "hides" the underlying PDEs [2].

[1] https://www.featool.com [2] https://www.cfdtool.com

Like half of my knowledge of physics comes from Mr. Wizard episodes from the 80s:

https://www.amazon.com/Mr-Wizards-World-Volume-1/dp/B00NL5PP...

They made a huge impression on me -- much more so than the classes I had in high school where everyone was just expected to blindly memorize formulas and no one understood any of the fundamentals.

I would recommend looking at Mark Rober's channel[1]. He's a NASA engineer turned YouTuber and does (weekly?) live lessons teaching kids physics through experiments. It's really fun to watch (and his catalog of non-live videos are good for kids too).

(I have no connection to this person, I just love what he's doing)

[1]: https://www.youtube.com/channel/UCY1kMZp36IQSyNx_9h4mpCg

Feynman's physics lectures: https://www.microsoft.com/en-us/research/project/tuva-richar...

Get her started with an Arduino kit! And then follow tutorials on Adafruit, SparkFun, Make: Magazine, etc. I always found circuit analysis to be a super dry topic when taught in my high school and college classes, but it's fun when you start out with the goal of building something. Depending on whether she's more interested in physics/EE/programming, you can delve into one of those areas more.

I was slightly younger than fourteen when my fifth-grade teacher staged a bridge-building competition in the class. She priced the raw materials (mainly toothpicks, glue, and string; I can't recall what the various exotic items were), and graded us based on ineffables such as teamwork and empirical metrics such as how much we spent on materials and how much weight the completed bridge supported.

You could ask her to build a trebuchet and explain why she built it the way she did. There's lots of online resources for that and it doesn't have to be too math heavy if she isn't yet studying F=ma, potential energy, kinetic energy, etc.

And if she is far enough along to know/learn those things then they can be applied to.

Hope this helps