(Within the Fédération Cynologique Internationale, the 'Russell terrier' is also known as 'Jack Russell terrier'.) The term 'Jack Russell' is also commonly misapplied to other small tan and white terriers. It is not uncommon for these dogs to become moody or destructive if not properly stimulated and exercised, as they have a tendency to bore easily and will often create their own fun when left alone to entertain themselves.Their high energy and drive make these dogs ideally suited to a number of different dog sports such as flyball or agility. Obedience classes are also recommended to potential owners, as Jack Russells can be stubborn at times and aggressive towards other animals and humans if not properly socialized. Despite their small size, these dogs are not recommended for the condominium or apartment dweller unless the owner is ready to take on the daunting task of providing the dog with the necessary amount of exercise and stimulation. They have a tremendous amount of energy for their size, a fact which can sometimes lead to trouble involving larger animals.