Right, most kanji have component parts, and if you can name and understand the component kanji, you can often guess at what the whole kanji means. This is very intentional and really the way the Chinese first came up with these characters. Here by the way is the raw for page one
Kodomo no Jikan 55 RAW Read Online
Sayo did not translate the big characters on the lower left:
夏 "SUMMER" - "natsu" or "ka" -- a head hanging down over "walking legs"
海 "SEA" - "umi" already mentioned
青木先生 "BLUE TREE BEFORE LIFE" -- you (and the Chinese reader) must be puzzled by that sequence but it will become clear in the Japanese pronunciation, "AOKI SENSEI"
実家 "REALITY HOUSE" "jitsu" "ie" -- in other words his real home.