Every day, as our children are growing we have so many questions about how to continue raising them bilingually. Lately, we have had an encounter with our 1st grader. It is the issue of reading.
How can we help our our son learn to read in his second language but also help him with his English reading at the same time? It has been a challenge in both languages!
From what you say, I understand that your son has just started his introduction to literacy skills (reading and writing) in school. This school training will make him aware that speech can be represented by means of printed symbols.
I also understand that he is being taught these skills in English only, in school. This means that he will learn one specific set of spelling conventions, those that associate letters of the Roman alphabet to sounds of English. You don’t say which other language it is that you want to teach him literacy in, or which alphabet/set of printed symbols it uses. If you (not the school) want to teach him reading and writing in another language, you may want to ask yourself why you wish to do this.
Your son may have use for literacy skills in another language, for example, or you may simply wish to take his budding awareness about what reading and writing are all about to generalise it to another language. Whichever your reasons are, he will have to learn that printed conventions differ from language to language. This is no problem, because he already knows that words, for example, also differ from language to language.
Even if you decide not to teach your son literacy in any other language than English, my guess is that he will sooner or later start asking you questions about this. There are bound to be books in different languages at your home, which will prompt his curiosity. For example, with two languages that use the same alphabet, he may start reading words of language X using the spelling conventions of language Y (and even make this a game), or wonder whether a particular letter is used in the same way in both languages. This is also a way for him to learn to read and write in another language, which leaves the initiative of doing so to him.
Do feel free to contact me privately, if you wish to discuss these matters in greater detail.