The EPI article Schools are still segregated, and black children are paying a price by Emma García (2/12/2020) provides an overview of inequities in secondary schools. Figure B in the article is copied here and speaks clearly to issues of inequality by race. There is also a political perspective that the percentages hide. According to Table 2 on the Census Bureau page School Enrollment in the United States: October 2018 – Detailed tables, there were 1,214,00 13 and 14 year old black students and 6,058,000 white students. (Note 13 and 14 years of age is approximately 8th grade and the Census Bureau is 2018 data while the EPI graph here is 2017. ) What this means is that there are 1,214,000*0.724=878,936 black eighth graders in high-poverty schools and 6,058,000*0.313=1,896,154 white eighth graders in high-poverty schools, or over twice as many white student in high-poverty schools.
The EPI article has a total of four graphs with available data.