Remember the right word for "little"

(they are the basic meanings for " siu" and " sai3")

siu2 = a small amount of something (a pinch of salt)
sai3 = something which is small (a small house)

Primary school = siu2 hohk6 (literally: primary/junior study) NOT sai3 hohk6.

Btw, original meaning of " siu2 hohk6"(literally: junior study) is “primary philology”. Children learned shapes, meanings and pronunciations of characters before they went to school in accient China. They are right the primary/junior part of Chinese (languge).