Cut up the prints so that you separate the sentence from the picture. After cutting there are 6 pieces of paper from each A4 sheet. Have enough pieces of paper so that there is at least one for each student. If you end up with more than enough, it's not a problem, just give the remainder to selected students (who will then have 2 pieces of paper) and tell them that they are lucky. The students then get up and find the student with the matching paper, and together they bring them to you for you to check before finally sitting down. To make it a bit more challenging and worthwhile you can ask the students to not show the sentence/picture, but rather say it out loud. Also they could say the sentence to the teacher as they hand it in for confirmation.