Read some old newspapers from World War II. Longer paragraphs and a greater vocabulary were common, even in the unsophisticated Midwest.
Watch some of the movies of the 1930's. The actors spoke in longer sentences with complex sentence structure and a vocabulary rich with words we do not even hear today.
Part of this is due to the increased use of computers, which feed our "instant gratification" portion of the brain. I noticed last year that I was having difficulty reading long passages, and I believe it is because I am on the computer so much. I also noticed I hadn't been reading books much. I decided that I needed to bring back the long attention span I used to have, and have been reading books in the evenings.
Textbooks are also reinforcing the shorter attention span by catering to it. Just as Sesame Street created generations of children who wanted lessons that lasted no more than 2 minutes (complete with cartoons or puppets), the textbooks are now filled with pictures, cartoons and jolly bullet points to get the attention of children who have been raised on video games, computers, and TV.
Here is my scariest comment. I will bet that my post is one of the longest posts on this forum (in the replies). I have been here since 1998. Ten years ago it was quite common to see longer posts. (An example of this would be the late, great Common Tator.) I have been struck by how few posts are of any length now. And I will bet a lot of you had trouble reading this whole post, because it looked like too many words.
You make some excellent observations, Miss Marple. Like you, I attended elementary school in the 50's. Homework assignments were graded not only on their content but also on proper spelling and grammar. When my daughter (now 24) was in 8th grade, she brought home one of her better Social Studies reports, proud of the A she had received. Reading it through, I was appalled by the poor grammar and spelling errors. I called her teacher the following day to inquire about the oversight. She explained that students are graded on content, not grammar.
When you and I were growing up, we played outside. Neighbors exchanged conversations from their front porches. There was a genuine sense of comaradie. News broadcasts were limited to 30 minutes and covered the news, not scandals. Television time, if one were fortunate to have a set, was restricted. Foods were cooked from scratch. In fact, there were very few restaurants near our home in Queens NY. Today, on the other hand, chains of restaurants proliferate the same thoroughfares, neighbors rarely talk and the news broadcasts run 24 hours / day, filled with gossip and rumors. Worse yet is the amount of taxes we pay for something that is labeled education. Text messaging has replaced English and many of our youth prefer instant meals over those made from scratch.
Thank you both for imparting your memories and wisdom, to this thread.