How can i stop my kitten "begging" for food?

my kitten is about 12 weeks old now, and due to kitchen space we dont have a dining table at home. we have always just sat on the sofa in the living room. but recently our kitten has started to climb up and try and snatch food from our plates. she is very persistant and even did a flying ninja jump form the other sofa this morning into my bowl of cornflakes. as you can imagine - cornflakes EVERYWHERE! its funny, but i have to stop her doing it and no amount of telling off, or putting down on the floor is helping. we try and feed her at the same time as we eat too but she is not interested in her own food until we have finished ours!