Help a teacher out with teaching stocks.

I'm a HS math teacher, this upcoming school year I've been given a newly created course that is similar to Financial Algebra. The course covers banking, credit, employment, budgeting, retirement, taxes,…, and stocks.

I problem is that I have never invested in stocks. The pacing guide says to spend 2wks (10 school days) on it, and really I am only mandated to cover simulating a stock portfolio and explaining the benefits of diversifying, so I don't need to get into the nitty gritty of things, just what your average American may experience when wanting to invest in the stock market (and note that this is a remedial course, some of these kids on my roster aren't going to college and a few may not even graduate HS).

I'll probably use MarketWatch's paper/simulated stock market “game” to have students pretend invest. Rather than what I experienced as a student, where the economics teacher just said that we have $10k and to email them all our transactions (so it only involved immediate transactions, and I had to manually keep track of my portfolio).

However, there are just so many questions I have that students will have too, as well as things I just don't really know. So help is very much appreciated.

• Say I have shares of a small stock that doesn't have a large volume of transactions and I want to sell; if I want to sell at market rate, is it immediate? Do I have to wait till there are buyers available?

• If a share was $100 at 10am, if it's $110 at 11am can I sell all my shares at that price immediately, and if it's down to $90 at 1pm can I immediately buy those stocks, and if it's $120 at 3pm can I sell them all immediately?

• Do all transactions occur at market rate (related to first question)? I somewhat familiarized myself with limits/stops, but I'm not talking about that. For instance, say I have shares in a stock that go for $100, can I have a friend buy them off me for $80/share (say I'm tired of the volatility or just it's just a discount I'm giving to him, like if I owned a rental property and a buddy wanted to buy it off me)?

• What benefit is there going with a broker that changes transactions fees compared to going with something like Fidelity/ETrade?

It's information such as this that I really don't currently get and would appreciate any help.