Being in the 2nd grade he has known the alphabet for a long while and he knows how to put things in alphabetical order as long as they all start with different letters. I had to explain to him how to go further and check the subsequent letters for putting items that start with the same letter in order. He caught on pretty quickly.
Our first lesson was to take one of each of our print moveable alphabet out onto a rug. He then put them in alphabetical order. I wrote some words on small pieces of paper and he put the words under each letter of the moveable alphabet. Then he told me which word was first and which was last. We had some words that started with the same letter and even some that had the same first and second letter, so I showed him how he had to check each letter to determine which would come first.
Next, we picked some random words to look up in our dictionary. He picked his favorite animal first, which is the Polar Bear. Then he chose words for things in our classroom such as Frog and Book. We looked them up and read the definition of each.
Finally, he chose a word on his own, Cactus. He spelled it out with the moveable alphabet. Then he found it in the dictionary and read the definition.
After he had done a couple of these we moved on to a workbook that I recently purchased. I found this workbook at a local teacher supply store that was going out of business. I thought it looked pretty helpful for practice so that he doesnt have to come up with his own words to look up all the time.
This particular workbook has one book for grades 1-3 (which we have) and another that goes more in depth for grades 4-8.