The key is in the "p"

The phrase watching your p's and q's has been passed down for generations.

For little children this phrase reminds them to make sure they haven't switched the letter "p" with the letter "q" and/or vice versa.

For more experienced writers in the English language, it helps us remember to check our work before we turn it in; it helps us prepare for the grade that we will receive.

However, the letter "p" plays a much more prominent role in our lives than you might, at first, suspect. Check it out!