When I hear "teaching portfolio" I think examples of the faculty's pedagogical approach and assigments, then students's work samples, and then faculty's evaluations of the work.  Is that what you mean?

Citizen, Yes, exactly: Some examples of student work, examples of my work that I used as a guide for teaching (sometimes), and short writing on the what, why and evaluation of my own teaching. My teaching portfolio is formatted in the same presentation layout as my design portfolio--lots of images and some writing. Do you think it's typical to add this kind of materials to job-seeking design portfolios? Or would that be distracting and confusing?

I think it's fine.  But the only way you should include this is as a kind of appendix, or clearly separate section of your portfolio.   That way it shows what else you've been up to (corresponding to your cv/resume), and clear that you consider this work important to your overall experience but not directly related for the jobs you're seeking.

Good luck!

I have one page of students' work in my portfolio, toward the end, titled "Examples of Student Work".  There are four images, one for each of the courses I've taught in the last year. I don't include any "whys" of my teaching, or any evaluation of my own teaching - I really doubt anybody will read those things if you do include them.  On my resume I include my teaching experience in a separate category from architecture experience, and list all the institutions and courses at each.