General knowledge about scripts
Keep in mind that most European languages use Latin letters. These letters represent speech sounds. However, the sounds these letters represent may vary per language. For example, in German “z” sounds like [ts], but in (European) Spanish it sounds like “th” in English “thing”. Also, in many languages there are more speech sounds than Latin characters. Languages differ as to how they solve this problem. Some use combinations of letters to represent a speech sound, others use diacritics. Examples are Spanish “ñ”, which represents a [nj] sound, or “č” in Czech, which represents [tsj].
The relationship between characters and the speech sounds they represent is not equally straightforward in all languages. In Italian and Spanish, this relationship is very straightforward. Each letter is pronounced in a fixed and predictable manner. In English, however, it is a lot more complicated. “ea” for example is pronounced one way in “heart” and another way in “heard”, and in “beard” it is pronounced in yet another manner. Dutch takes the middle road: the relationship between characters and the speech sound they represent is not as straightforward as it is in Italian or Spanish, but it is more predictable than it is in English.
Not all languages use the Latin alphabet. Many Slavic languages such as Russian, Serbian and Bulgarian use the Cyrillic alphabet. Greek has its own script. Even though the letters found in the Greek and Cyrillic alphabet are different from those in the Latin alphabet, all of those letters represent speech sounds. This is also true for the Arabic script. One difference between the Arabic script and the Latin, Cyrillic and Greek alphabets is the fact that Arabic letters mainly represent consonants. The writer or reader has to “come up with” the vowels him or herself. In practice, this is not very complicated as Arabic only has a limited number of vowels. The Arabic language does have characters that represent vowels but they are mainly used in dictionaries and in education, to teach children about the correct pronunciation of words. In most written texts, they are not used.
Some languages use a script that does not represent sounds but meanings. An example of such a language is Chinese. The basic unit of Chinese writing is the radical. This represents a certain meaning. By putting radicals together, you create characters. Most words consist of several characters, all of which contribute to the meaning of the word. Some radicals can be used for more than just to represent meaning. Some are added to characters in order to indicate pronunciation, sort of like you do with a rebus. In that case, the (original) meaning of the radical is irrelevant. Chinese people are not unfamiliar with the Latin script. In the 50s, the pinyin system was developed: a spelling system that uses Latin letters and diacritics, intended to represent the pronunciation of Standard Mandarin (the official Chinese language). This system is used in, for example, education, to teach children who speak different Chinese languages and dialects at home about the pronunciation of Standard Mandarin, and to help them learn about the pronunciation of the various characters in Chinese writing.
This means that, at the intake of new pupils, teachers should check which kind of writing system the child is familiar with. Also, it is important not to treat pupils with non-Latin or non-alphabetical writing system (such as Chinese) as illiterate. As was mentioned, other alphabets are also systems that represent sounds, and sound representation plays a role even in Chinese. Besides, children raised in China are normally familiar with (a variety) of the Latin script.