WASHINGTON — On Friday, Michelle Obama will begin digging up a patch of White House lawn to plant a vegetable garden, the first since Eleanor Roosevelt’s victory garden in World War II. There will be no beets (the president doesn’t like them) but arugula will make the cut.

While the organic garden will provide food for the first family’s meals and formal dinners, its most important role, Mrs. Obama said, will be to educate children about healthful, locally grown fruit and vegetables at time when obesity has become a national concern.

In an interview in her office, Mrs. Obama said, “My hope is that through children, they will begin to educate their families and that will, in turn, begin to educate our communities.”

Twenty-three fifth graders from Bancroft Elementary School in Washington will help her dig up the soil for the 1,100-square-foot plot in a spot visible to passers-by on E Street. (It’s just below the Obama girls’ swing set.) Students from the school, which has had a garden since 2001, will also help plant, harvest and cook the vegetables, berries and herbs.