I’m saying that the work they would be doing in two days isn’t the same as solving an actual problem. The way to really learn a language/framework/library is to actually use it in a real project. You run into pitfalls, you get compile errors and have to figure out how to debug in said tech, you find out how extentions to the tech work so you can create your own. Making a Todo Front End isn’t going to cover the vast majority of the stuff I’d expect one to know or experience when you say you “know” a language/framework/library/etc.