One of the many delights of doing magic with children is their total honesty. If you make a mistake, or they think they know how it’s done, they tell you in no uncertain terms (& praise you to the skies for a good one). This is why ‘Colour Card Vanish’ is such fun (my favourite of all I make): you WANT the audience to think you’ve made a mistake. Kids will always point out (erroneously) that you have (while adults are usually far to ‘restrained & polite’ to do so!). You then show that THEY are the ones to have made the mistake!