I think that it is nice to mix up the letters instead of doing them in order but it has an added benefit that this makes it easier for the kids.
The lower case letters are different orders but we do both capital letters and lower case letters at the same time.
When I was teaching my son, I made a list of all the words that started with a certain letter and a list of all the books that had things to do with that letter. There are great resources all over the internet but I love the list of the books from Measured Mom because there are so many different ideas. We had a rough idea that we would use a lot of different ideas to learn the letter such as:
- reading books with the letter
- doing arts and crafts to make things with the letter
- learning math dealing with the letter (my son's favorite subject)
- using writing with the letter
- using fine motor skills with the letter
- using sensory items with the letter
- incorporating science with the letters
- singing songs or learning rhymes with the letter
Enjoy and have fun!!