The natural world

You met 天 (tiān) as the day, in 今天, 昨天 and 明天. Here is the rest of it.

天 is also the sky. 天空 (tiān kōng) is the sky as an expanse, sky-emptiness. 天气 (tiān qì) is the weather: sky-energy, using the same 气 you met inside 生气, to get angry.

夏天 (xià tiān) is summer, and so are all the seasons: 春天, 秋天, 冬天. Each is a season-character plus 天. Learn one and you have four.

The reach of a single character is the thing to take from this session. 天 gives you the days, the sky, the weather and the seasons, which is a large slice of ordinary conversation from one component.

气 is worth chasing

气 (qì) is air, breath, gas, and vital energy. It is inside 天气 the weather, 生气 to get angry, 客气 polite, and 空气 the air you breathe.

There is no single English word that covers it. The nearest is something like animating force, which sounds mystical and is not meant to be: in ordinary modern usage 气 is simply air or mood, and the philosophical sense is a specialist reading rather than the everyday one.

Hot and cold are simple

热 (rè) is hot. 冷 (lěng) is cold. Both are adjectives and both take 很 rather than a verb: 很热 is it is hot, with no verb to be anywhere in the sentence.

That is worth restating because it catches people for months. Mandarin adjectives ARE the predicate. Adding 是 to say it is hot produces something ungrammatical.

The animals

狗 (gǒu) dog, 猫 (māo) cat, 马 (mǎ) horse, 鸟 (niǎo) bird.

马 is worth a look, because it is also the sound component in a large number of other characters, including 妈 (mā) mother and 吗 (ma), the question particle. The horse is not involved in either meaning; it is there purely to tell you how the character sounds.

Roughly eighty percent of Chinese characters work this way: one part for meaning, one part for sound. Knowing that turns the writing system from a memory test into a system with rules.