My first attempt to post this expired. Let's see if this works. I'm attempting to reply to your follow-up question.

It's conventional for popular descriptions of Chinese characters to describe them as being symbols of the MEANING of the character, with no particular relationship to how the word being written is pronounced. That's why many people informally call Chinese characters "ideograms." Let's see if I can resort to Unicode here and put some Chinese characters into my reply.

Plainly, the characters

一 (one)

二 (two)

and

三 (three)

are visual representations of tally marks and can be taken to be ideographic characters. The relationship of these characters to the underlying pronunciations of the WORDS (which are yī, èr, and sān in standard Mandarin) is entirely arbitrary.

But most Chinese characters, since the earliest stage of what can properly be called writing in Chinese, have been mostly sound-indicating. The pattern of historical development is that the language spoken at that time had a lot of words, which in the case of early Chinese were mostly although not quite entirely words consisting of one-syllable meaningful parts (morphemes), some of which were readily pictureable (e.g., horse, fish, mountain, woman, tree) but many of which were not. Ancient scribes would find a sound-alike word, or a close-enough-for-government-work similar sounding word, to represent nonpictureable words, and mark the distinguishable usage of that written character with "radicals" that broadly indicated what semantic category the sound-alike word belonged to, for ease of reading.

Here is a list of Chinese characters that all have the pronunciation /fang/ (in various tones) in Mandarin:

方 放 房 訪 防 芳 仿 妨 紡 坊 肪 枋 倣 舫

I think your eye can spot the common visual element in all those characters. The "proper" way to use each of the characters is to associate it with a particular word (really, morpheme) that has a particular meaning. But one could, in principle, use any of those characters to write any syllable /fang/ that appears anywhere in the Chinese language, and the reader reading aloud would still know from context which morpheme pronounced /fang/ was intended by the writer. Boltz points out that there is actual archeological evidence that Chinese writers more than 2,000 years ago were moving in the direction of using Chinese characters solely for sound value in writing (as shown by their using the "wrong" sound-alike characters in many inscriptions) and they could have gone all the way to what Japanese did in developing systems of syllabary characters that can exhaustively write all sounds in the spoken language with no more written characters than the language has syllables.

P.S. I asked about textbooks above, because no Chinese society had mass literacy until elementary pupils in Chinese-speaking countries were taught to read first by using sound-indicating writings systems (alphabets in all actual cases) as a first step in teaching literacy. In Taiwan, as before in Nationalist China, the zhuyin fuhao (BO PO MO FO) alphabet, with written alphabetic characters based on the shapes of parts of traditional Chinese characters, has long been used for this purpose, and in general any pupil who has completed first grade can write anything that anyone can speak in that system. The P.R.C. since the 1950s has used the elegant Hanyu pinyin Roman alphabetic characters for the same purpose.

P.P.S. An interesting and rather astounding link

http://english.peopledaily.com.cn/200501/03/eng20050103_1695...

shows that for a long time Western writers have been overestimating the number of inhabitants of China who are actually conversant in Mandarin. The lower than expected percentage of Chinese persons who can understand one another in Mandarin illustrates how little provision of primary education, broadcasting, or telephony has reached the hinterlands of China. The comparable percentage in Taiwan, which a generation ago had a much lower percentage of families with any family heritage of speaking Mandarin, is much higher, a sign of Taiwan's greater success in providing education and mass communications to all inhabitants.

Please ask follow-up questions as needed.