You don’t expect many partners at white-shoe law firms to make the transition to the quick-footed world of the Web. But David Feinberg, 41, is doing just that. In February, Feinberg left a comfortable perch at Foley, Hoag & Eliot LLP, a top Boston firm, to become president of Schoolsuccess.net. The young Internet company offers child assessments and customized content to parents and teachers, as well as to a wide range of organizations. Along with a staff of about 23, Feinberg is working to create strategic partnerships with children’s museums, activity centers, and child-care providers such as Bright Horizons. OLD SKILLS THAT STILL MATTER “Being a lawyer is all about using critical-thinking skills. I challenge every single fact or statement to make sure that it’s correct, whether it’s a financial projection or an assessment of the customer base at a child-care center.” LEARNING CURVE “In the Internet economy, perfection is the enemy of progress. As a lawyer, I used to spend a lot of time planning how to move forward. But at a dot-com, there’s just not enough time to make everything perfect.” TEACHING NOTE “A dot-com business must work under old-economy metrics. You have to make sure that you’ve got a revenue model that will result in a profitable company — not ‘someday,’ but in the foreseeable future.”