It's that time of the year again – the time when I update my annual count of how much peer-reviewed research has been published on flipped learning. I started doing this in 2016 while I was writing my book on flipped learning and I have done updates every year in June since then. Here are the 2017, 2018, and 2019 updates that show the research from 2016, 2017 and 2018 respectively.

The process for doing this count goes like this: Go to the educational research database at http://eric.ed.gov/.  Then, to get the data for 2019 (which is what I'm doing in this post), run the following search and make sure to check "Peer reviewed only":

(title:"flipped learning" or abstract:"flipped learning") and (pubyear:2019)

Then write down how many results the query brings back; it's listed near the upper right of the page. Then repeat this with flipped classroom and then inverted classroom in place of flipped learning. These are currently the three most common terms used to refer to flipped learning, so the data (and the sum of the data) give a reasonable proxy for how much peer-reviewed research on flipped learning was published in 2019.

The usual caveats apply: This is just a back-of-the-napkin calculation and not a professional-grade literature review. The search query only takes place on one database, for instance. The queries could return false positives since all we're doing is looking for papers where "flipped learning", "flipped classroom", or "inverted classroom" appeared in either the title or the abstract; there could be papers that fit that description that are not really about flipped learning. And it's possible (I'd say likely) that some papers are double- or triple-counted because they mention two or more of those three terms in the abstract.

Still, this is the good-enough-for-a-blog-post method I've been using to count research on flipped learning since 2016, so at least we can say that the results from year to year are comparable. And for most years, we've seen a consistent pattern of exponential growth in the number of peer-reviewed flipped learning publications from one year to the next. Most years – but not all. In last year's update, which counted research published in 2018, there was a noticeable drop – 180 publications versus 192 in 2017. While the cumulative total of published research continued to grow exponentially, we were left wondering if perhaps published research on flipped learning was starting to level off or even decline.

So, how did things go in 2019?

Here are the results of the search queries for 2019 and the differences compared to 2018:

Search term Number of publications in 2019 Difference from 2018
Flipped classroom 150 +23
Flipped learning 69 +18
Inverted classroom 4 +2
Total: 223 +43

Here's a chart of the yearly data (it cuts off the "223" on the top right point for some reason):

Published research on flipped learning by year, 2000-2019
Published research on flipped learning by year, 2000-2019

And, as I did last year, the cumulative graph of flipped learning research calculated as a running total from year to year:

Published research on flipped learning by year, running totals 2000-2019
Published research on flipped learning by year, running totals 2000-2019

And since this definitely looks like exponential growth, here's a plot of the yearly data with a regression model:

Published research on flipped learning by year, 2000-2019 with exponential regression
Published research on flipped learning by year, 2000-2019 with exponential regression

The formula for the model (with the time rescaled so x = 0 is the year 2000) is $y =0.809122(1.35217)^x$  with $R^2=0.9277$.

I've got three takeaways from these results.

First, it's pretty clear that flipped learning research rebounded strongly in 2019, and research is more prolific than ever. I don't have any good ideas as to why, other than just saying that more and more faculty must be getting interested in the flipped learning concept, and as faculty get more comfortable using flipped learning, they are more inclined to study it through SoTL projects involving their own students. And the more research that's out there, the more faculty will have a basis for doing their own research.

Second, a word about growth rates. The exponential model says that flipped learning research as of January 2020 is now growing at a rate of 35% per year. With that annual growth rate, a little precalculus says that at this rate, flipped learning research will double in published output every 2.3 years. That's slower than it was back in 2017 when the growth rate was an astonishing 88% per year — we're seeing the global effect of last year's slowdown. Still, show me an another educational research area where the publication outputs are growing this fast.

And that gets me to the third point: I think next year this update will be extremely interesting due to Covid-19 and the Big Pivot. From my perspective, the Big Pivot to online teaching has brought a resurgence in interest about flipped learning – although that interest is coming as a package with interest in online teaching and learning more generally. Even though we normally think of flipped learning as something that involves significant face-to-face time, people are thinking of it right alongside hybrid or online pedagogies – which I think is appropriate and I'll have more to say about that soon.

Still, I will decline to make predictions for research output from 2020, for one simple reason: All of us in higher ed right now are way too busy with trying to get online teaching right, or even just "acceptable", to do research on flipped learning right now. In fact I think we will probably see the number drop again next year, not because of flagging interest in flipped learning – on the contrary, serious interest seems to be at an all time high right now – but because everyone interested in teaching and learning is focused on classroom instruction right now.

Looking at the search queries the 2020 as the year, as of June 15 there are 18 publications for "flipped learning", 47 for "flipped classroom", and none for "inverted classroom". That's 65 total, which is only 29% the total output of 2019 even though we're halfway through the year. On the other hand, this time last year (June 3, 2019) the total publications for 2019 were only 52, and 2019 as we've seen was a big year for flipped learning research. So who knows? It will be interesting to watch.

Finally, another usual caveat: Quantity does not imply quality. As I mentioned on Twitter three years ago:

I'm sorry to say that I haven't kept up well with the published literature on flipped learning – or anything else – over the last year. (Along with my lack of discipline for making time to read research, I blame a cascading series of life-changing events that started back in August 2018 for me and hasn't let up yet.) But I will say that what I have been able to read seems more polished than in the past, with better questions and methodology than the old "I tried this in my class and a few students liked it" approach to "research" that used to be de rigeur. This could be selection bias, since the older I get, the better able I am to sniff out bad research and the more inclined I am to avoid it. I am hopeful, though, that we're not only getting more research on flipped learning, we're learning more from it.

One last word: The data from 2000-2019 are freely available via a Creative Commons license on Figshare at the DOI below. The citation to use if you're using the data is:

Talbert, Robert (2020): Published research on flipped learning 2000-2019. figshare. Dataset. https://doi.org/10.6084/m9.figshare.12482048.v1