What to do when a seizure happens

To add on to this. It used to be said that you're supposed to put something in their mouth (like a wallet) to keep them from swallowing their tongue or something like that (the idea being that their mouth would be open a little bit, so their esophagus wouldn't be open all the way, so the tongue wouldn't fit down it), however this is actually a really bad idea for two reasons. One, because the muscles in their jaw can tighten up and if something's their, they could damage their teeth and/or jaw. And two, it's not actually possible for a person to swallow their own tongue. This is an outdated speculation that is not true.