The first series was called Wonders in Letterland, but I can't remember a certain "Something" about the following series'.

"Something"-Bag Strikes Again
"Something"-Bag Bounces Back
Turn on to "Something"-Bag
"Something"-Bag's Christmas Cracker
"Something"-Bag and the Revenge of the "Something"-Set
"Something"-Bag's Christmas Carol
"Something"-Bag and the Pearls of Wisdom
"Something"-Bag's Christmas Ding Dong
"Something"-Bag and the Rings of Olympus
"Something"-Bag's Christmas Turkey
"Something"-Bag and the Sunstones of Montezuma
Take Off with "Something"-Bag