A sonnet is a formal poem with a fixed structure. It is 14 lines long and each line contains 10 syllables. Sonnet lines are in iambic pentameter which means the line has 10 syllables in 5 pairs. In each of these pairs the emphasis is on the second syllable like a heartbeat. You could play the sound of a heartbeat or ask the children to feel their pulses to understand this. 

The rhyme scheme in an English sonnet is ABAB, CDCD, EFEF, GG.

Sonnets often pose a question which is answered in the final couplet.

In the example below Rachel Rooney has played with the form to create her poem. It is a 14 line poem with 10 syllable lines but Rachel has not followed the rhyming pattern rules.