It's sad to think our kids won't truly understand why we dial or hang up a phone, why cashiers ring up our purchases or why we roll up our windows without doing some homework.
Which means either these expressions are due for an update or those who remember are going to have to teach our young about those days of long ago when we had to manually turn a window crank handle to open a window.
And if you really want to relate to the youth of today you can discuss the origin of the expressions "going on line" and "posting to a message board":
13. WHY DO WE SAY "ON LINE" FOR COMPUTER THINGS?
In the early days of computing, when one machine needed to communicate with another, they had to be attached with a physical cord or "line." Processes that could be completed without this communication were "off line."
10. WHY DO WE CALL IT A MESSAGE "BOARD"?
Before the internet, when people wanted to make an announcement or share information they would put it on a piece of paper and attach it to a board mounted in a public location where many people would see it.
See 15 Common Expressions Younger Generations Won't Understand at Mental Floss
Author is plain ignant.
That use of "online" is still present in phrases like "Online Transaction Processing" (OLTP), where "workloads are characterized by small, interactive transactions that generally require sub-second response times", or in "online algorithm", which is "one that can process its input piece-by-piece in a serial fashion ... without having the entire input available from the start."