Suggestion on where to meaningfully spend 20 hours of learning on programming

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I am asking this question from a quite specific situation, so allow me to elaborate a bit. Recently, I decided to make a job change to be a teacher (primary school btw, likely 10-11yr olds) - one of the subjects I have now is 'ICT in education'.
The final assignment for that is a free-to-spend 20 hours on whatever ICT-related subject I see fit and feel motivated to do. Just need to prove I spend those hours, and that it can cross over in any (even if far fetched) way to education, like to inspire them or something.

I briefly took up a course of C# 6 years ago, and learned some principles and basic concepts (data types, loops, inheritance,... ) even though it all really needs refreshing and some of what I learned might be out-of-date (no idea really). I remember getting stuck a bit on implementing event handling (got our first kid too, which was the other reason to make me drop it).

Given that context, does 20 hours seem reasonable to get some background under my belt, maybe try to make some simple projects - anything that can prove it was a 20 hours meaningfully spent.
Also, it does not need to be C#, maybe some other language or tool would be more meaningful to start afresh. Wichever (freeà avenue might yield something meaningful in the field of ICT (for me and the kids at some point).
I consider it meaningful if:
- it provides me with deeper insight in what programming logic is about, and capable of
- it serves as a realistic stepping stone to continue exploring afterwards (I don't need to stop at 20h should I feel warmed up - it just won't be for the assignments)
- it actually might yield some basic but somehow cool project
- from the above points, ideally it can help me to motivate pupils, and help me to get them interested or provide some inspiration in this field

So I want to decide if spending 20h makes sense, and I could reasonably propose it - or if I will just forfeit fundamental programming and go for something very applied instead (making cool presentations, working with digital schoolboards, ... all nice, but not my first choice).

So what do you suggest, C-sharp, anything else out there - or just to drop it alltogether under these conditions? Thank you all in advance!

What I have tried:

Have studied C-sharp for 7 months, 6 years ago, up until getting stuck on the projects we were making - integrating WPF and event handling, things like that.