Combine maple syrup, soy sauce and pepper; mix well.
Cut each chicken tender crosswise into quarters. Place in large plastic food storage bag with half of the maple syrup mixture.
In another plastic storage bag, place shrimp and remaining maple syrup mixture. Refrigerate chicken and shrimp 3 hours or overnight.
Heat broiler, grill pan or gas grill or prepare charcoal grill with hot coals. Thread 4 pieces of chicken onto each skewer. Thread 3 shrimp and scallions onto skewers (see Note).
Coat broiler pan with nonstick cooking spray. Arrange chicken skewers on prepared pan; broil 4 inches from heat for 3 minutes. Turn chicken skewers; add shrimp to broiler pan. Broil chicken and shrimp skewers 3 minutes, turning shrimp once halfway through. Or grill chicken a total of 6 minutes, shrimp for 3.