Are canadian public high school free for american citizens?

its about my sister.shes american,but lives in bangladesh with the family.now shes in 9th grade and we'r concerned about her education.however my parents cant afford to send her to private school in usa.in addition we dont hav any relatives in the usa,but we do have relatives in canada.so she can stay at their place and go to school.will going to canadian public school free for her,since she is an american citizen.any advice.???