This product is a fantastic resource for teaching lower and upper case letters, as well as sounds. The resource contains separate lower and upper case flash cards which I have found work well back to back.
There is also a set of flash cards which contain photos for each letter (Aa - Apple).
The sound cards are for varying levels depending on the development of the student. Some have pictures to match the sound eg: 'ai', a picture of a train, whereas some as simply the sound: 'ai'. I have used this working with students with disabilities of recent weeks and encouraged them to think of words with that particular sound.
If the sound cards are created back to back, and the letter cards back to back you result in 3 packs of flash cards. However; this is entirely up to you!
Hope you enjoy :)