The South Orange-Maplewood School District has launched an investigation after an Olympian publicly accused a teacher of pulling a hijab off the head of a 7-year-old Muslim student in school on Wednesday. Ibtihaj Muhammad, a 2016 Olympic medalist in fencing and a Maplewood resident, wrote on her social media accounts Thursday that a teacher at Seth Boyden Elementary School in Maplewood “forcibly removed the hijab of a second-grade student.” Muhammad’s connection to the student is not clear. “The young student resisted by trying to hold onto her hijab, but the teacher pulled the hijab off, expo…