Answer of your this question changes with the nature of the person to whom you are going to teach about BITCOIN. Well lets say, its child having no knowledge or a old man having less knowledge. You should start from the basics. like.

• what blockchain is and how btc is dependent on blockchain technology,
• Use cases of blockchain technology.
• What are smart contracts. and importance of impact that they can make.
• What is ledger, distributed system, concept of centralization and decentralization
• also teach them how banks works and how they control your money to get there advantage. This will open there eyes

There is more on the list but the density of above explanation changes with the nature of opponent's mentality. As we at least can know by asking him how much he/she knows or simple  judge it without making fool of them.
Your way is also good but do not start with exampling stoshi this will make things more complex like how many stoshies are there in 1 btc and how many btc are there in 1 satoshi this is not math. This is innovation and trend of blockchain that revolutionizes not only financial sector but a lot of other sector of life too.

Well, basic functioning and fundamental impacts that a new technology like btc can make on future should be the main context of your teaching's scenario. and that depends on you how would you teach them with what approach but before teaching them do some practice like on your self and ask questions to your self. That will also groom yourself too.