Cinquains are a form of syllabic poetry characterised by a distinctive 5 line structure:
1st line: 2 syllables
2nd line: 4 syllables
3rd line: 6 syllables
4th line: 8 syllables
5th line: 2 syllables

They can be written as a riddle, as in this example by James Carter, from his book Let’s do Poetry in Primary Schools!, where the last line reveals the subject of the poem.

A fire.
An inferno.
A blazing, gazing eye.
And one golden, open oven…
The sun.

Alternatively, the first line can be the subject of the poem, the following lines adding description, movement through the use of adverbs, a phrase describing the scene and a re-stating of the subject, perhaps in a more elaborate form. The following cinquain demonstrates this.

Frozen liquid
Falling, drifting, dancing
Covering everything in white