
Dual differentiation is a key educational pedagogical approach for all committed to the success of twice-exceptional (2e) learners (Baum et al., 2001). Has this approach become more widespread since 2001? One way to investigate this question is to utilize big data visualization techniques such as the Google Books Ngram Viewer (Google Ngram). is a search engine tool that can be utilized to visualize trends over time. Google Ngram allows for frequency tabulations of word searches in books published between 1800 to 2019 in various languages such as English (American English, British English), French, Italian, Russian and more.
Figure 1 above shows the Google Ngram for the terms “gifted education”, “special education” and “dual differentiation” between 1800-2019. 1964 has been highlighted as the year the term “special education” began to increase rapidly in books. As we take a closer look at the “special education” book publication peak in 1996 (Figure 2)

books that contain the term “special education” was appearing 51 times more frequently compared to books containing “gifted education” and 6,625 time more frequently than books containing “dual differentitation”. Books containing “Gifted education” appeared 130 times more frequently compared to books containing “dual differentiation.

From figure 3, we can see that by 2018, “special education” terms are found approximately 13.7 times more frequently in books compared to “gifted education”, and 2,270 times more frequently compared to “dual differentiation”. Books containing “gifted education” was 166 time more frequent compared to “dual differentiation” books. “Dual differentiation” books have increased 332 times in frequency between 1996-2018.
When we add in books on “education” to compare with “gifted education”, “special education”, and “dual differentiation” using the 1964 year from the above exercise,

the change in the scale of our perspective paints quite a different picture as shown in figure 4. When we scale our perspective out to look from a macro or higher level of analysis, data visualization here shows us that we need more books written not only on “dual differentiation” but also for “gifted education” and “special education” since 1800! From this view, “gifted education”, “special education” and “dual differentiation” data looks flat, when in fact figures 2 and 3 show that special education books have been decreasing while gifted education and dual differentiation books have been increasing since 1996-2018.
The higher level wider scale perspective points out that within the context of education, we should be advocating for more books in areas of gifted, special education, and dual differentiation. Dual differentiation pedagogy arose from those involved with learners who demonstrate high potential with at least one area of disability that requires simultaneous dual differentiation considerations at all times to nurture holistic human development and success throughout their lifespan.
These various Ngram search terms demonstrate the importance of considering different levels of analyses simultaneously, in order to form a more holistic and complete understanding of any phenomena of interest. We need to apply this approach towards human development and growth as our children are influenced not only through our individuality but also through our immediate environments such as school and home, but also our larger environment including socio-economic-cultural influences.

Back to our initial question on how widespread has dual differentiation pedagogy become since 2001? The general answer is that although English language books that contain the term “dual differentiation” has increased 332 times in frequency between 1996-2018, it only represents 0.00000719% of all English language books which contain the term “education” in 2018, according to the results of Google Ngram.
References
Baum, S. M., Cooper, C. R., & Neu, T. W. (2001). Dual differentiation: An approach for meeting the curricular needs of gifted students with learning disabilities. Psychology in the Schools, 38(5), 477–490. https://doi.org/10.1002/pits.1036