Roofing shingles and methods for installing and making them

A roofing shingle having a bottom surface, the roofing shingle having an exposure zone at a lower end thereof and a headlap zone at an upper end thereof, the roofing shingle comprising:

• a first bituminous sheet disposed at the bottom surface of the shingle in the exposure zone thereof, the first bituminous sheet having a lower edge disposed at the lower end of the roofing shingle, the first bituminous sheet having one or more slits formed therein, each of the one or more slits extending from the lower edge of the first bituminous sheet toward the upper end of the roofing shingle;
• and
• a second bituminous sheet at least partially laminated to a top surface of the first bituminous sheet, the second bituminous sheet having a lower edge disposed at the lower end of the roofing shingle, the second bituminous sheet having one or more tabs formed in the exposure zone of the shingle, the one or more tabs being defined by one or more notches formed in the second bituminous sheet, each notch extending away from the lower edge of the second bituminous sheet.