When it comes to using pennies for dog training, the amount of coins you need will depend on how big your can is and what type of task you are trying to train your pup. Generally speaking, a good rule of thumb is to fill the can with enough pennies so that when shaken, it makes a loud rattling noise. This sound helps capture the pup’s attention during training sessions and encourages them to focus better on their tasks at hand. However, if you have a smaller can or want a quieter sound for teaching certain behaviors like “stay” or “come” commands then start off with about 100 - 150 pennies in the can first before adding more if necessary.