Mary Draper Janney, a former educator and family planning expert, yesterday announced her candidacy for the Ward 3 D.C. City Council seat and called for increased funding and improvements in the city's public school system.

Janney said she had visited several D.C. schools and was "appalled" at the conditions, which she said included leaky roofs, buckled floors and broken fire doors. Broken or inadequate fire doors "are winked at by fire inspectors on their yearly rounds," she said. "Is it really going to take a fire during school hours to get the Department of Public Works to do something about it?"

D.C. School Superintendent Floretta D. McKenzie and the school board have complained that the mayor and the City Council have recommended inadequate school funding for the coming fiscal year, and McKenzie on Friday suggested that she might quit if more resources are not made available.

Janney also told about 70 supporters at an announcement party yesterday that she is concerned about "unbridled development" in Ward 3 "that threatens the quality of life." She pointed in particular to three developments planned at Wisconsin and Western avenues and to new movie theaters being planned along Wisconsin Avenue, which she said will bring more traffic to the area. "The impact on residential neighborhoods will be enormous . . . unless controls are imposed," she said.

Janney is the fourth Democrat to enter the Ward 3 race for the seat now held by council member Polly Shackleton, who is retiring. The other candidates are Ruth Dixon, a newsletter editor and publisher; Mark Plotkin, a political consultant, and Jim Nathanson, a teacher and chairman of the Ward 3 Democrats.

In unsuccessful challenges to Shackleton in the 1982 Democratic primary, Dixon won 35 percent of the vote and Plotkin 18 percent. Nathanson has Shackleton's endorsement this year, but Janney said yesterday that she sees herself as following in Shackleton's footsteps.

"She may not support me, but I sure support her," Janney said of Shackleton.

Janney was a founder and president of Wider Opportunities for Women, a group that helps unemployed and underemployed women, and she was executive director of Planned Parenthood of Metropolitan Washington for four years until 1983. She has served on the mayor's task force on teen pregnancy.

She taught history for 12 years and is chairwoman of Vassar College's board of trustees. She is a Vassar graduate and has a master's degree in sociology from Yale University.