Group 2: for children weighing 15 - 25 kgs (33 - 55 lbs), roughly 4 to 6 years. Booster seats that only fit into Group 2 are less common. Most are group 2 and 3, or groups 1, 2 and 3. Groups 2 & 3: for children weighing 15 - 36 kg (33 - 79 lbs), roughly 4 to 11 years.
Broil the ribs for about 5 minutes, until the sugar in the dry rub is bubbling and the ribs are evenly browned. Bake the ribs: Set the oven to 300Â°F. Move the ribs to an oven rack in the middle of the oven. Roast for 2 1/2 to 3 hours for spare ribs or 1 1/2 to 2 hours for baby back ribs. Halfway through cooking, cover the ribs with aluminum foil to protect them from drying out.
1 Preheat grill to medium-high. Remove ribs from marinade, reserving remaining marinade. Cook ribs for 8 minutes, turning a couple of times, until golden brown.  Boil remaining marinade for a minute or two and pour it into a small bowl or gravy boat.