Talking with an Australian

Today I met a new Australian friend who wanted to learn Mandarin Chinese and to know more about Chinese culture. We talked in Mandarin and English alternatively for two hours. We were both strict and fastidious toward(s) (not sure about the use of fastidious, never used it) each other, trying to detect and correct the mistakes that the other (one) made. I, as a native Mandarin speaker, was not good at tenses. I occasionally made mistakes like using the present tense where I should have used the past tense instead. And my friend, he had trouble with the four tones in Chinese. In English, a rising, falling or even (a) flat tone doesn't change the meaning of a word. They are (related to) the same word. However, in Chinese, any single pronunciation (maybe use a different word, like syllable, here?) has up to four tones. For most cases, each tone will have a corresponding character and meaning. So in Chinese, tones are very important. I think we could discovery more interesting things about a our languages in our future talks.