If you are travelling on Route 2 westbound, take Route 128/I-95 south. Your next exit is Trapelo Road/Lincoln. 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.