It could be anything but presumably it is to see how you work with Y1 children as much as how you teach. My Y1's love anything that could involve moving round, singing, making, they likeeveryone being happy and gentle, they don't like unclear explanations. Year 1's tend to want to please. Instructions for Y1 have to be short and not too many at a time and repeated a few times. If you aren't too sure on phonics have a quick look at some of the letters and sounds resources that are around, most of my Y1's are on phase 4-5 at the moment. Interviews are often reading a book with an activity, my Y1's are always desperate to see the pictures! Have fun with them and good luck!