Study grammar, sentence construction and general English for a specific facet of the language to write about. Possibilities include, but are not limited to, articles of speech, verbs or adverbs, adjectives, nouns, pronouns, verbs, subjects and several others. Alternately, you could choose to do a general approach encompassing many parts of speech.
Decide which approach you'll take and how many you'd like to include. Since you'll want the poem contained to a manageable length, plan to focus on 8 to 10 parts of speech.
Create a word-bank using the parts of speech you've decided to use. Include a definition next to each word for help with writing the poem.
Write end-rhyming couplets of two sentences using a particular part of speech and a creative definition. You can choose to incorporate the part of speech into the rhyme or not, either will work. For example: "Every name is called a NOUN,
As field and fountain, street and town."
Continue creating rhyming couplets, if you want them to rhyme, for each part of speech you've selected. Consult a rhyming dictionary for help.
Memorize the poem by repeating and reading it several times. Recite the poem both with and without the written version.