Only Slate Plus members can gift Slate stories. Become a member to share 10 free articles a month. How many vowels does English have? Five, right? A, E, I, O, U. Oh, and sometimes Y. So, six? Actually ...

These "I" and "E" vowels are formed by putting your tongue forward in the mouth. That's why they're called "front" vowels. With these words, your tongue depresses and folds back a bit. So "O", "A" and ...

Consonants are the rest of the letters in the alphabet: b, c, d, f, g, h, j, k, l, m, n, p, q, r, s, t, v, w, x, y and z The letter 'y' is a bit different, because ...

It's hard to pinpoint when synesthesia, the rare neurological condition where a stimulus that affects one sense prompts a response in a different sense, was first documented. Scientific literature ...