It takes 2000 kanji to be able to read the newspaper. Japanese students learn them all the way from kindergarten to the last year of high school. These characters are associated with meanings, and many have several different sounds. Here are some combinations:

record 記 + sense 念 = memory 記念
sky 天 + feeling/mood 気 = weather 天気
remaining 残 + sense 念 = regret 残念
sky 天 + country 国 = heaven 天国
hot 熱 + heart 心 = passion 熱心
change 科 + study 学 = chemistry 科学