I unfortunately can't find it either, but this month I heard a talk by Madeline Di Nonno, the CEO of the geena davis institute, cite that it is in 4th grade (~1

I unfortunately can't find it either, but this month I heard a talk by Madeline Di Nonno, the CEO of the geena davis institute, cite that it is in 4th grade (~10yrs old) when there is a marked drop off in interest in STEM for the reasons you list. likely more at their site: seejane.org