This is a 1976 Schwinn Scrambler, Model BX1-6. Back in its heyday this motocross bike was one of the coolest on or off the road. According to a 1976 Schwinn Bicycle Catalog:
"It is a specially designed model with heavy duty construction and motocross features built-in. Every frame joint is reinforced with extra welds. The cranks are of hardened steel. The handlebar has a welded on brace and the forged handlebar stem is built to take it. Specially designed Schwinn motocross tires with an exclusive deep studded tread design for a sure grip on varying surfaces. The new Schwinn Scrambler - ideal for off-the-road, and equally at home on the road for those who demand a sturdy, sporty bike."
Early on Schwinn became known as the Cadillac of American Bicycles. They produced a number of popular, quality bicycles. Some of the more popular children's bicycles were the Krate series and their Stingrays. The Scrambler was a very similar bike to the Stingray, some of the major similarities were in the frame, stem, seat post and clamp.