R.M.
Hi S.,
I have been working with kids for 16 years as a preschool teacher and a Nanny. I always developed some sort of lesson plan for the kids in my care, but when it comes to 2.5 year olds, it's less about ABC's and more about concepts. Up/Down, In/Out and especially cause & effect. 2 year olds love to explore things, learn how they work and understand why there are there. I suggest purchasing a magnifying glass, (make sure it's safe), and let her go to town! She will love looking at the world.
With that said, singing the ABC song, pointing out colors, number and letters is also important, but will mean little to your 2.5 year old. The brain develops in a certain way, so helping her understand certain concepts will help prepare her for the next stage in learning.
Good Luck!
R. Magby