TABLE 4.

Discouragement themes descriptions and sample quotes

Theme	Description	Sample quote
Social exclusion	Boys ignore, avoid, or exclude girls in STEM spaces.	There are some [male] students who will not talk to me just because I'm female. Tha’s really frustrating to me…I’s never easy responding to that situation. I have tried persistence and just trying to be friendly. Olivia, White, 11th grade
Physical exclusion	Boys assert ownership or control of physical material and spaces.	I can distinctly remember one time my group, we had to build instruments. We built a washtub base, and one of the guys in my group would not let me drill holes in the base or cut anything because he was like no, no, no, i’s like ‘this is like a guy's work’. I’s okay. You can chill for right now. Kiara, Black, 12th grade
Idea/identity ownership	Boys dismiss and/or take credit for ideas; or doubt that girls can be engineers/good at engineering.	It feels weird when you're working with a group of boys, and some boys are not as nice…[W]hen I'm in group work, and then I say something, and it sometimes feels like they didn’ really process what I said, but then this other guy says something similar, and then they're like, “Oh, yeah, tha’s right.” I'm like, “Whoa, I just said the same thing.” Isabella, Latinx, 11th grade