KanjiJLPT N5
Tall

tall, high, expensive

Mnemonic

A pufferfish puffs up enormously, stretching tall as a skyscraper. A tiny hat perches on its very top, barely holding on. Its wide mouth gapes open in shock at its own ridiculous height—the taller it grows, the more the hat wobbles and the mouth stretches wider!
Additional thoughts
Visualize the pufferfish inflating vertically like a balloon, the hat balanced at the peak emphasizing the topmost point, and the mouth stretched open below—mirroring the kanji's structure of hat on top, mouth in the middle, and the pufferfish body filling the frame.
Quick recall
A pufferfish in a hat opens its mouth in awe at how tall it's puffed up.

Details

The keyword for 高 is tall. This kanji represents the concept of height, elevation, or being high. It conveys both physical tallness, as in a structure or person of great height, and more abstract senses of being lofty, expensive, or superior in degree. It is one of the most commonly used kanji for expressing anything related to height or high status.
On'yomi
こう
Kun'yomi
たか.い、たか、-だか、たか.まる、たか.める