~時
~じ · ~ji · JLPT N5 · noun
clock
🕒 時 = sun 日 + temple 寺: temple bells by the sun told the hour
時 combines 日 (sun, day) with 寺 (temple), which also supplies the reading ji. Temples once rang bells to mark the hours. Attach it to a number: 三時 (san-ji) = 3 o'clock. Sound hook: ji starts like the g in gee, what time is it?
~とき · ~toki · JLPT N5 · noun
at the time of ~
⏰ toki = time; X + toki = at the time of X, i.e. when X
時 is the kanji for time, built from 日 (sun, day) + 寺 (temple): temples once marked the hours of the day. Attached after a verb or noun, とき turns it into a when-clause: 子供の時 = at the time of being a child.