Why this will change her behavior:

YOU ARE CHANGING THE ENVIRONMENT. Novelty creates opportunity and attention. In the traditional language of learning, they call the environmental stage the antecedent (A). It is the condition that triggers a behavior (B) in order to affect a consequence (C). Your dog has already figured out the ABC’s of a behavior (in this case, begging), and a certain stage is set (dinner is served at the table with her at your side). In this situation, if you expect her to stop the behavior, you are swimming against the tide of history. But reintroduce the situation with a new condition (she is leashed to the foot of the couch across the room with a bone before you serve the meal), and you’ve gotten your dog’s attention. This prevents her from engaging the old habit automatically, and gives you the chance to answer the How can I . . . ? question (in this case, How can I . . . get your dinner?) that she is suddenly asking again.

YOU ARE MANAGING THE LEARNED HABIT. If a behavior continues to work out well for your dog, she will continue to do it. Life might be reinforcing her for continuing to beg (people do drop yummy things regularly, especially when kids are involved), and her brain is chemically rewarding her for trying even when she fails. It is an impossible cycle to break unless you manage it (your dog is leashed to that couch whenever food is served) to prevent it beginning at all. Be diligent about preventing your dog from begging around meals by using leashes, doors, baby gates, crates, etc., until you have adjusted the behavior.

YOU ARE EXPLOITING THE GENETIC MOTIVATION. You will never persuade your little scavenger to lose interest in table scraps, but you can put her love of them to work for you. It is in her DNA to seek leftovers from human meals. Once you have played the first two cards, you can win the hand by putting the force of this genetic impulse to work for you rather than against you. At the end of your meal, put some leftovers or other goodies in her bowl only if she remained quiet while you ate.

YOU ARE MINDING THE SELF. A young puppy has far less impulse control, attention span, and maturity than an older dog. However, she also is behaviorally far more creative and experimental, without the baggage of habits in her way. An older dog may have maturity, but also has had plenty of time to practice bad habits. If your dog was recently rescued from conditions in which she was starved, it may take her longer to learn to control herself around food than if she were fat and happy.