notes, key, explanation, understanding
觧 centers on making something clear or understandable: providing notes, keys, or explanations that lead to understanding.
觧 is a variant form of 解. The left side 角 (horn) and right side 羊 (sheep) suggest the idea of dissecting or separating parts of an animal, which extends to analyzing and explaining. The exact historical relationship between 觧 and 解 is uncertain, but they share the core meaning of unraveling or clarifying.
A horn 角 and a sheep 羊 together: imagine using a horn to carefully part the wool of a sheep to examine and explain what lies beneath, like making notes or giving a key to understanding.
For カイ, picture a guide using a horn to part the sheep's wool and saying 'Here's the key!' — 'key' sounds like カイ, and the explanation becomes clear.