This is a fun, often-eye-opening activity for students and teachers alike. Using guiding questions, students evaluate their teacher's own classroom for gender bias. I've used this with high school students of all ages, and it often helps students to understand how spaces can be gender-imbalanced, and helps me work on making my room more inclusive.
I recommend doing this as a partnered activity. Document is one two-sided worksheet with introductory context copy, guiding questions, graphic organizer for notes, and reflection questions.
While this is designed as a classroom evaluation, you could also easily modify the language to make it a gender analysis of almost any text or space.