Spelling.School · How to spell

How to spell a

What it means: Used before a singular noun to mean one.

In a sentence: A cat sat on the mat. ▶

The part people get wrong

Often misspelled as adenine or á.

Same family: nucleotide, DNA, base-pair, genetic, adenosine. If you can spell one, the shared part carries to the others.

Where it comes from: In genetics, the lowercase letter a is used as a simple symbol for adenine, one of the four DNA bases. The name adenine itself comes from the Greek word “aden,” meaning “gland,” because it was first isolated from animal glands.

Try spelling it

You will hear the word and a sentence. Type it and press Enter. Then four more words from the same level, so you know where you stand.

Words like this

play · sky · table · day · wake · say · okay · playmate

Spelling.School is a spaced-repetition spelling practice: ten minutes a day, every word spoken aloud, every miss explained, and every word coming back just before you would forget it. Try five words without signing up.