This is a 15-20 minute filler activity I made for my Spanish/Catalan-speaking students, which aims to check their awareness of the common mistakes they make when speaking. There are 16 incorrect sentences written based on the most common mistakes I've heard, and I give them 10-15 minutes to try and correct them individually or in small groups and then we go through it together. So far it's kept them all concentrating very hard and between the group we can usually get all the answers except for "explain to", so I explain that to them with this blog post http://www.englishteachermelanie.com/vocabulary-how-to-use-the-verb-explain/ I guess you could use this with native speakers of any other language but I designed it based on the common mistakes I hear from Romance Language speakers (plural agreement issues, incorrect gender pronouns and verb use .etc). I've left it a word file instead of a PDF so you can add things you hear a lot or cut down on the sentences for lower level groups.