"He was here in the '60s, during the struggle. That's why he wanted it here," said Rushing, the Indianola principal.
Moses, originally a New Yorker, had worked in the Delta, braving threats and assaults to register voters and organize blacks.
His return to this place and to the classroom fits well with his earlier activism, said Taylor Branch, author of the civil rights history "Parting the Waters."
"He saw the dividing line between whether you had a chance or not in Mississippi (in the '60s) was whether you could vote," said the historian, who has attended some Algebra Project workshops and has been impressed with the students' excitement.
"Now it's whether you could pass first-year algebra. I think he still sees that sharp dividing line between whether you have a chance or not."
Frank Davis, a math professor who is conducting a three-year evaluation of the Algebra Project under a MacArthur Foundation grant, agreed. "Bob Moses is a community organizer primarily," he said.
So, while teaching math skills, the Algebra Project attempts to create support networks of parents, local college educators and others to back up the students and their teachers; it attempts to retrain teachers. "It really is changing schools," said Davis, who teaches at Lesley College in Cambridge.
Moses said the curriculum is written so that no student starts at a disadvantage. Each builds on his or her own experience, using his or her own language. Thus the subway trips that kids take in Boston, the bus rides in the Delta, and the maps and reports and formulas they derive from them.
"Mathematics should get constructed by the students as much as possible based on these experiences," he said.
Shirley Conner, who oversees the Algebra Project at a school in Hollandale, Miss., said she believes it will make students look differently at their island in an ocean of cotton fields and catfish farms.
Their bus sojourn, where kids logged the Yazoo River Bridge, the Sunflower River and other landmarks and then "mathematized" the information, had energized them.
"We have no theaters, no McDonald's," she said. "We don't have a transit system, we don't have traffic lights."
And yet the students had had an experience many hadn't had before, she said: a sense of "ownership" of math.
"And when they get to handle it as their property, they can learn," she said. "The students learn to enjoy."