[Viliam1234]

In this case, a better solution could be to organize the activity at a place where black people live, but allow anyone to join.

Okay, this addresses the race, not sure what to do about gender. Maybe choose a stereotypically girly topic and make posters in pink color, but again allow anyone to join, I guess. Send a signal, don't close the door.

[whimsicalism]

This is a good solution and also a pretty common one, since public school districts not under a court order aren't allowed to explicitly consider race.

I grew up attending a "Saturday academy" sort of STEM program where I was the only white kid in a cohort of perhaps 50. It was open to anyone, but because they reached out to Black families and were in a Black neighborhood, they were able to target without having strict, exclusive rules.

Just targeting places with lots of Black people is definitely a huge improvement over what we currently do.