Ann and Donald really changed a lot throughout this series!
The reason I say this is that recently I bought 6 episodes (5 from 1966-1967 season, One from 1970-1971) and between those episodes, they REALLY did change!

By the 1970-1971 season, the theme song was in place (There was no theme song in the first season, just an instramental), and Marlo and Ted's characters were firmly in place also.

By then, Donald had that 'It's 1970, I'm in my 30s, and proud of it!' hair cut. By then Ann didn't have her flip anymore :( Her hair really was LONG by then! She looked more in the times. In the first season, she wore more 'Daddy's Girl' clothing, IE sorta simple clothing (Such as in 'Anatmony of a Blunder' where they go out for a picnic), but now she was wearing more of the really in clothing, she wore a choker (!!!) in some of the episodes, and they had little flowers embodied in them.

Major Snaps to this series. The show was great during it's entire run!

Yeah, they did change alot. I like that her style changed and got with the times. It was nice to see a different hair do too. I also like the theme song in the 5th season because it has the words. :)

What an interesting observation. I have noticed a lot of changes by the 4th season; especially in Ann Marie's wardrobe. She seemed to be more hip and daring; and also, by the 4th season, she was growing her hair, longer and more in tuned with the style of that late 1960s and early 1970s.