Research on class size and participation of women in undergraduate STEM courses

This 2019 paper by Ballen et al in BioScience entitled “Smaller Classes Promote Equitable Student Participation in STEM” is worth reading if you’re interested in equity, teaching, and STEM.

This large study (with 26 co-authors!) attempts to determine which features of undergraduate STEM classrooms correlate with more equitable vocal participation of women through a careful analysis of 5300 student-instructor interactions in 44 courses (observed over a full term) at six different institutions (4 in the U.S., 1 in Egypt, 1 in Norway). Answer: (1) class size was most impactful, followed by (2) the number of different strategies that the instructor used to elicit students’ vocal participation in class.

Educational literature up to this point has been very mixed about the connection between class size and student learning (see OECD 2012 report, CampbellCollaboration 2018 report, and many others). This is the first paper in which I’ve seen a strong argument for reducing class size: lowering class size increases the likelihood that women will participate in undergraduate STEM classes. In their data, increasing class size from 50 to 150 students decreased the likelihood of a woman participating by 50%.

The researchers were also able to reject several alternative hypotheses with their data. These alternative hypotheses included connections between equitable vocal participation and (1) abundance of student-instructor interactions per class period, (2) instructor gender, (3) proportion of women in the class, and (4) whether the STEM class was lower- or upper-division. (In other words, none of these things significantly correlated with more equitable participation.)

But since class size is often out of the instructor’s control, what can one do to make participation more equitable? The researchers found that instructors using a large repertoire of methods of eliciting vocal participation from students also got more equitable participation. (This makes me wonder, however, whether the size of an instructor’s repertoire of methods for eliciting student participation might correlate with instructor’s overall skill.) The article gives at least 7 different strategies that instructors can use to elicit students’ contributions in a classroom:

1) increase wait time between posing a question and selecting someone to answer in front of the whole class
2) using think-pair-share before selecting someone to answer
3) letting students work in small groups
4) having students write first before sharing out loud
5) soliciting multiple volunteers and calling on students only after a certain number of students have raised their hands
6) assigning student groups a number and using random number to select a group to answer
7) assigning a student in a group to be the “reporter” based on some arbitrary characteristic (e.g. random number or who woke up earliest)

I have a few more:
8) in addition to having good wait time, when posing a question to the class that you want students to respond to, select concise and clear wording for your question prompt, display the question on the screen (if possible) while reading it, and avoid that awkward continuous rephrasing of the question as a way of filling the silence
9) using vertical non-permanent surfaces (like white or chalk boards) to make student work visible before having students share ideas verbally to the whole class
10) positioning incomplete, partial, incorrect answers as being valuable to classroom discourse so as to lower the social risk for students to participate in whole-class discourse
11) using Google docs or equivalent online platforms to allow students to simultaneously contribute their ideas in an online space (this idea doesn’t involve vocal participation like the others, but it still involves students articulating their ideas in front of others)

Because the researchers’ posited reasons for women participating in class less than men involve imposter syndrome and social identity threat, that means these results should also to students of color in undergraduate STEM courses as well. In addition, I can see that many of the same arguments will also apply to secondary schools.

Characteristics of Effective Teacher/Faculty Professional Developent

Note: This blog post is based on a presentation that I gave at the 2019 MathFest in Cincinnati during a contributed paper session entitled “Professional Development in Mathematics: Looking Back, Looking Forward, on the Occasion of the 25th Anniversary of MAA Project NExT” organized by Dave Kung, Julie Barnes, Alissa Crans, and Matt DeLong.

For over 15 years, I have designed and led professional development for K-12 (mainly PCMI and MfA LA) and higher-education faculty (mainly Claremont Colleges Center for Teaching and Learning), primarily to help others enhance their teaching and learning.  I never received any formal training in how to do this kind of work, but I was fortunate to have worked alongside other educators in the field (Ginger Warfield, Gail Burrill, Peg Cagle, Pam Mason, and many others) and I have tried to learn as much as I can from the education literature.

Professional development for both K-12 and higher-education faculty is crucial if we want to continually improve the quality of education for our students and to reduce the loss of talent and resources that comes from faculty turn-over. And yet, anyone who has gone through professional development trainings and workshops knows that the main problem with professional development is that not all of it is good. In fact, some professional development is just plain awful. Bad professional development not only turns people off from wanting to continue to advance their skills, but it also muddies the waters about whether money spent on professional development is worthwhile.  However, the reality is that we are continually learning more about what effective teaching looks like and that information needs to be disseminated to teachers and faculty, so we will never stop needing good professional development for teachers and faculty. Moreover, “one constant finding in the research literature is that notable improvements in education almost never take place in the absence of [teacher] professional development” (Guskey, 2000, p. 4).

There is much less published research on the professional development of higher-education faculty than there is for K-12 teachers. This makes a lot of sense because there are many more K-12 educators than there are higher-education faculty and much more is spent on K-12 teacher professional development than for higher education faculty. I believe there is a lot that folks doing professional development for higher-education faculty can learn from what has been written about in the K-12 world.

Recently, I did an extensive literature search to find research on what effective K-12 teacher professional development looks like (not limited to mathematics). I found over 30 years of research commentaries, empirical studies, and meta-analyses that try to characterize effective professional development (Banilower, Boyd, Pasley, & Weiss, 2006; Birman, Desimone, Porter, & Garet, 2000; Blank & de las Alas, 2009; Borko, Jacobs, & Koellner, 2010; Darling-Hammond, Hyler, & Gardner, 2017; Desimone, Porter, Garet, Yoon, & Birman, 2002; Garet, Birman, Porter, Desimone, & Herman, 1999; Garet, Porter, Desimone, Birman, & Yoon, 2001; Little, 1993; Loucks-Horsley et al., 1987; Loucks-Horsley, Stiles, Mundry, Love, & Hewson, 2010; Stein, Smith, & Silver, 1999; Timperley, 2008; Timperley & Alton-Lee, 2008; Wilson, 2013).

There is a remarkable amount of consistency among all of this scholarship. To demonstrate this, I’ve selected three papers from the 16 papers listed above and summarized their lists of characteristics of effective PD below.

Loucks-Horsley, S., Harding, C. K., Arbuckle, M. A., Murray, L. B., Dubea, C., & Williams, M. A. (1987). Continuing to Learn: A Guidebook for Teacher Development. The Regional Laboratory for Educational Improvement of the Northeast and Islands; National Staff Development Council.

Characteristics of effective K-12 teacher professional development:

  1. Collegiality and collaboration
  2. Experimentation and risk taking
  3. Incorporation of available knowledge bases (by this they mean that teaching practice should be informed by research and validated in model programs and practices)
  4. Appropriate participant involvement in goal setting, implementation, evaluation, and decision making
  5. Time to work on staff development and assimilate new learnings
  6. Effective leadership and sustained administrative support
  7. Appropriate incentives and rewards
  8. Designs built on principles of adult learning and the change process (andragogy—the practice of teaching adult learners; includes opportunity to try new practices, guided reflection and discussion, time for significant change, balancing support and challenge)
  9. Integration of individual goals with school and district goals
  10. Formal placement of the program within the philosophy and organizational structure of the school and district (by this, they mean that it cannot be the effort of a few energetic individuals, it must be embedded in the organizational structure and culture)

Garet, M. S., Porter, A. C., Desimone, L., Birman, B. F., & Yoon, K. S. (2001). What Makes Professional Development Effective? Results From a National Sample of Teachers. American Educational Research Journal, 38(4), 915–945.

Characteristics of effective K-12 teacher professional development:

  1. Focuses on subject-matter content and how students learn it
  2. Includes opportunities for teachers to become actively engaged in meaningful discussion, planning, practice
  3. Professional activities are coherently organized around goals that align with state and district standards and procedures
  4. More contact hours over a longer time span allows for learning to sink in
  5. Collective participation of people from the same school, department, or grade level is more helpful than participation of individuals from many different schools

Darling-Hammond, L., Hyler, M. E., & Gardner, M. (2017). Effective Teacher Professional Development (p. 76). Retrieved from

Characteristics of effective K-12 teacher professional development:

  1. Is content focused
  2. Incorporate active learning
  3. Supports collaboration
  4. Uses models of effective practice
  5. Provides coaching and expert support
  6. Offers feedback and reflection
  7. Is of sustained duration

I hope that you see many connections between the items on these three lists. And the same is true if you look across all 16 papers.

Based on this survey of the literature and my own experiences doing this work, here are a few important takeaway messages for people who lead and design professional development for both K-12 teachers and higher-education faculty. These ideas are oversimplifications, so you’ll need to think about how they might apply in your own context.

First of all, learning takes time and being able to see evidence of change takes even more time. We should not expect much to happen from a one-time 90-minute workshop. Programs that happen over longer periods of time are more likely to lead to real change in behaviors. This seems pretty obvious and yet a lot of professional development programs rely on the one-time workshop model.

Second, we need to make sure that the work that we are doing is aligned with the realities of the institutional (schools, districts, colleges, universities) and departmental contexts faced by participants in our programs.

Third, authentic community is important because it supports collaboration. Having some shared context is one way to create an authentic community.

Fourth, program evaluation is crucial. This is not an item that we see in the lists above, but it is one that I have found to be true based on the work I’ve done so far. Effective professional development efforts are ones that can document growth and success over time, both for ourselves and for our stakeholders and potential funders. That documentation requires us to be strategic about program evaluation and assessment. We have to get much better and smarter at how we evaluate our programs. Not everything can be quantified, but we can’t let the challenge of measuring progress keep us from constantly improving through program evaluation..

I don’t think these characteristics are necessary and sufficient conditions for professional development to be effective. I suspect they are only necessary at best. There are probably other conditions that are required too.

What do you think are essential characteristics for teacher/faculty professional development to be effective?


  • Banilower, E. R., Boyd, S. E., Pasley, J. D., & Weiss, I. R. (2006). Lessons from a Decade of Mathematics and Science Reform: A Capstone Report for the Local Systemic Change through Teacher Enhancement Initiative. Retrieved from Horizon Research, Inc. website:
  • Birman, B. F., Desimone, L., Porter, A. C., & Garet, M. S. (2000). Designing Professional Development That Works. Educational Leadership, 57(8), 28–33.
  • Blank, R. K., & de las Alas, N. (2009). Effects of teacher professional development on gains in student achievement: How meta-analysis provides evidence useful to education leaders. Washington, DC: Council of Chief State School Officers.
  • Borko, H., Jacobs, J., & Koellner, K. (2010). Contemporary approaches to teacher professional development. International Encyclopedia of Education, 7(2), 548–556.
  • Darling-Hammond, L., Hyler, M. E., & Gardner, M. (2017). Effective Teacher Professional Development (p. 76). Retrieved from Learning Policy Institute website:
  • Desimone, L. M., Porter, A. C., Garet, M. S., Yoon, K. S., & Birman, B. F. (2002). Effects of Professional Development on Teachers’ Instruction: Results from a Three-Year Longitudinal Study. Educational Evaluation and Policy Analysis, 24(2), 81–112.
  • Garet, M. S., Birman, B. F., Porter, A. C., Desimone, L., & Herman, R. (1999). Designing Effective Professional Development: Lessons from the Eisenhower Program [and] Technical Appendices (No. ED/OUS99-3). American Institutes for Research.
  • Garet, M. S., Porter, A. C., Desimone, L., Birman, B. F., & Yoon, K. S. (2001). What Makes Professional Development Effective? Results From a National Sample of Teachers. American Educational Research Journal, 38(4), 915–945.
  • Guskey, T. R. (2000). Evaluating Professional Development. Corwin Press.
  • Kennedy, M. M. (2016). How Does Professional Development Improve Teaching? Review of Educational Research, 86(4), 945–980.
  • Little, J. W. (1993). Teachers’ professional development in a climate of educational reform. Educational Evaluation and Policy Analysis, 15(2), 129–151.
  • Loucks-Horsley, S., Harding, C. K., Arbuckle, M. A., Murray, L. B., Dubea, C., & Williams, M. A. (1987). Continuing to Learn: A Guidebook for Teacher Development. The Regional Laboratory for Educational Improvement of the Northeast and Islands; National Staff Development Council.
  • Loucks-Horsley, S., Stiles, K. E., Mundry, S., Love, N., & Hewson, P. W. (2010). Designing Professional Development for Teachers of Science and Mathematics (Third).
  • Stein, M. K., Smith, M. S., & Silver, E. (1999). The development of professional developers: Learning to assist teachers in new settings in new ways. Harvard Educational Review, 69(3), 237–270.
  • Timperley, H. (2008). Teacher professional learning and development (No. Educational Practices-18; p. 32). International Academy of Education.
  • Timperley, H., & Alton-Lee, A. (2008). Reframing Teacher Professional Learning: An Alternative Policy Approach to Strengthening Valued Outcomes for Diverse Learners. Review of Research in Education, 32(1), 328–369.
  • Wilson, S. M. (2013). Professional Development for Science Teachers. Science, 340(6130), 310–313.