游标卡尺

• 氵(water; liquid)RADICAL
• 斿(flag flutter; pennant wave)PHONETIC

Water flowing like a flag fluttering in the wind evokes the image of swimming and wandering.

• 木(wood; timber)RADICAL
• 示(sign; mark)PHONETIC

A wooden sign (标) is made from wood to display directions for everyone.

• 上(above; top)ASSOCIATIVE
• 卜(divination; insert downward)ASSOCIATIVE

Something stuck is what stays on top and cannot come down, blocked from moving.

• 尸(body lying down; prone body)RADICAL
• 乚(hook; curve)ASSOCIATIVE

A ruler is imagined as a person lying straight with curved fingers marking the length.