From link below:
Obama first noted that he had worked with Planned Parenthood to push a sex education bill when he served in the Illinois state legislature.

Then he said: “I remember Alan Keyes—I ran against Alan Keyes—but I remember him using this in his campaign against me, saying, ‘Barack Obama supports teaching sex education to kindergartners.

“And you know,” said Obama, “I didn’t know what to tell him. But it is the right thing to do, to provide age-appropriate sex education, science-based sex education in the schools.”

[link to cnsnews.com]