Here are some of the things that I’ve noticed have changed over the years.
When my kids were babies, it was okay to lay them on their stomachs when sleeping. Now it is best to lay a baby on its back. It was fine to give a baby a bottle in the crib; now it isn’t.
When I was growing up, eggs were supposed to be good for you. Then they weren’t, and now they are okay. I recently read an article that said if you are healthy and your cholesterol level is normal, it is okay to eat as many eggs as you like. But reduce saturated fats (bacon, red meat, whole milk and other dairy products) and avoid the trans-fatty acids in junk foods, fried foods, and potato chips. Eggs are one of the healthiest foods you can eat.
When I was going to college, treating sport injuries was different than now. I think they have made a lot of improvements in that area.
When I took driver’s education, we were taught if driving on the highway, the distance to keep between you and the car in front was one car length for every 10 miles per hour you were driving. For example, if you were driving 50 miles per hour, you should keep five car lengths between you and the car in front. I don’t think that is true anymore. Anyway, people don’t follow that rule. I guess if you did, you wouldn’t ever get a chance to pass anyone if you wanted to because cars would get between you and that other car, and you would never get anywhere. We were also taught not to change lanes while in an intersection, but I've seen people do that. I was taught another thing that was not a law, but rather was a safety thing, I think. When pulling up to a red light, stop so that you can still see the rear tires of the car in front of you. This is because if a car behind you fails to stop in time and hits you from behind, you probably won't hit the car in front or, if you do, it won't be as bad if you were any closer. I don't think people do that nowadays.
There is one thing that hasn’t change since my college days (late '60s)—if you eat too much and don’t exercise, you are going to gain weight. To lose weight either eat less or exercise more. It is best to do both.
You too could probably think of some other things that have changed, or stayed the same.
I can think of a few.
When starting up from a red light, let the car in front of you get at least
half way into the intersection before you start. This has saved me from
hitting a car in front of me a couple of times. Didn't save me from getting
hit though. Poor policeman. He had to write up 2 accidents. No one seems to
follow this rule anymore.
When I had my babies, mom's stayed in the hospital for 5 days. Now the norm
is overnight, if there is no problems.