Travel southbound to Route 128 South. Follow the DeCordova signs to exit 28A-B, Trapelo Road. Take a right on Trapelo Road. You will drive approximately 3 miles to Lincoln center, a five road intersection. Sandy Pond Road is directly ahead. The DeCordova Museum is approximately 1/2 of a mile on your right.
You might find it helpful to print these directions and bring them with you when you travel.