I have not decided if this is a good idea or not. As a former Div 1 shortstop I do not advocate teaching kids sweep tags as they will miss the runner on a number of occasions. Straddle the bag and place the glove in front of the bag. The runner has to come to the bag, right? No matter the technique you will be cleated if you play enough. I have two scars from being cleated while turning two and one from the shortstop coming down on me after receiving a high throw from the catcher on a steal.
Girls, if someone is teaching you to block the bag with your legs, don't. A catcher with guards is a different story as long as she has been taught the correct way but no blocking bags, please.