If I could, i'd do shape and space mental. It sounds like a contradiction, but it works. Go over vocab ( edge, vertex etc) and then play barrier games with one person drawing the shape the other person is describing. It really forces them to think. And it's fun!
If not, for the mental i'd play games finding multiples, or halving and doubling. Everyone does tables. It's also far easier to differentiate halving / doubling.
For the full lesson I would always rather do literacy. Why not go for a word class focus lesson ( you can always ask about ability and setting beforehand, even a table plan, I did my last interview!) ? I'd find out their topic and plan accordingly. I would starter with word classes, visual images and find examples of all word classes from images of their topic.This can be done as a table. Same image each table or not, up to you. Then i'd work towards, in a lesson, a focus on writing using expanded noun phrases, or maybe fronted adverbials ( obv, differentiated) based on writing a paragraph from a clip of film or image. Continuing from a stop point works well. I like using "Raintown", an animation on Youtube, you can stop and say...."What happens to him?" (A robot, left to drown.) Lots of modelling, a bit of group work, some individual work, sharing at the end, drawing out good examples.
I've found whizz bang doesn't work for me in interviews, but less is more does.