土壤學

土 = 十 + 一 : Tommy Turtle (tu) wants to fix a cross (十) on a flute (一) in the space station's living room (Ø3). He uses dust and clay (土) to hold them together.

壤 = 土 + 襄 : Robinson Crusoe (r) and many others are working hard in a communal effort (襄) to analyze the soil (壤) in the Angwor Wat (ang3). They are digging up a lot of dirt (土) and want to analyze which layer of soil (壤) is the best one for agriculture.

学 = 小 + 冖 + 子 : Xu Xian wants to study scienceology and learn more about daisies. Just inside the elevator's kitchen, he put some daisies into a prize cup and covered them with a cooking top. He wants to study the growth rate of the daisies depending on the pH of the water in the prize cup.