There's a private school I teach at and they don't show the alphabet in their own native language. I was told not show the alphabet in english because they say it would confuse the children and complications would come about later on, is this true?

Personally, I think they should be taught both. There's really not much difference between the two (only 4 additional letters in Spanish). The English alphabet is only marginally helpful to overall learning, though. When children learn the Spanish alphabet, they learn the pronunciation of all the letters in Spanish, which is much more helpful since it's a phonetic language. In English, children pretty much just learn the names of the letters. As far as causing complications later, it really shouldn't unless this is a systemic problem in which children are not being taught anything in their native language. That could cause a cultural disconnect which will cause confusion and could cause a crisis later in life. Hope this helps.

native and second language for the alphabet should be taught side by side...it would be helpful if you will incorporate it with visual materials and sounds.

Basically this is correct. The children have an oral language with has its symbols. The child will read faster if taught in his own language. Once this occurs, the child will understand sound/symbol relationships and may immediately progress to oral/aural English and introduction to the English alphabet.

Retired teacher that taught ESL for 30 years.

I would follow the guidelines of the school you work for, just to be safe. Realistically, they should be able to be introduced to both at an early age. The earlier, the better. Children have a better ability to understand languages and it's when they're introduced to languages later that it becomes difficult.

Still, the school has to dictate the curriculum. So do your best to work in that particular environment.

Matt