Education
Highly Qualified or Highly
Unqualified? A Longitudinal
Study of America’s Public High
School Biology Teachers
SAMUEL J. POLIZZI, JEREMY JAGGERNAUTH, HERMAN E. RAY, BRENDAN CALLAHAN, AND GREGORY T. RUSHTON
In this report, we trace the historical demographic features of biology teachers, the largest disciplinary education workforce in science between
1987 and 2007, using data from the National Center for Education Statistic’s Schools and Staffing Surveys. While growing in size by more
than 50% during this period, this population became increasingly inexperienced and less male dominated. Biology teachers also were drawn
primarily from in-field degree graduates and remained racially homogeneous. We synthesize our data with previous studies to conclude that
biology teachers are most likely among all science teachers to teach outside of their discipline as part of their workload. We discuss consequences
of a large, highly qualified teacher population stepping outside of their content area for part of their course load, as it relates to self-efficacy and
professional identity. Implications for large-scale STEM education reform and a scientifically literate US population are examined within the
context of these findings.
Keywords: education, history, policy/ethics, statistics
N
ational concerns about the readiness of the science, technology, engineering, and mathematics (STEM)
workforce have been raised in US reform documents from
the National Academies (National Research Council 2005,
2010) and the White House (PCAST 2010, 2012). National
plans to revitalize the STEM workforce strategically target
both students and educators (Lander and Gates 2010, Gates
and Mirkin 2012), recognizing the multiplicative effect of
“10,000 teachers educating 10 million minds” (National
Research Council 2010). As a result, initiatives have emerged
to increase the supply of K–12 teachers with a focus in STEM
(e.g., UTeach, National Science Foundation Robert Noyce
Teacher Scholarship Program, Physics Teacher Education
Coalition, Teach for America, and Woodrow Wilson
Fellows). We have previously proposed that the aggregation
of STEM initiatives and concerns may lead to a diffusion
of responsibility, in which distinct stakeholder communities (e.g., discipline-specific teacher groups) do not take
responsibility for action because they assume others have
already acted (Rushton et al. 2014). Henry and colleagues
(2012) recently disaggregated discipline-specific teacher
groups and found significant differences in teacher effectiveness. As a result, they urged the education community and
the readership of Science to consider “distinctions between
STEM and non-STEM teachers, and even among STEM
teachers who teach different courses” (p. 1121).
Data on the distinctions among STEM teacher groups are
currently available for examination. Nationally representative data on the US teacher workforce have been compiled
by the National Center for Education Statistics (NCES)
using the Schools and Staffing Survey (SASS) and Teacher
Follow-Up Survey (TFS) six times between 1987 and 2007
(Goldring et al. 2013). As we exemplify below, we find that
published analyses of these data fall broadly into four categories: large grain size, longitudinal (Ingersoll and Merrill
2010); large grain size, short-term (Ingersoll and May 2012);
small grain size, short-term (Lyons 2013); and small grain
size, longitudinal (Rushton et al. 2014).
Large grain size studies have revealed the aggregate levels
of all teachers (i.e., STEM and non-STEM combined) and
science and math teachers. Longitudinal studies revealed
seven trends in the aggregate teacher workforce: the K–12
teaching population has become (a) larger, (b) older, (c)
less experienced in teaching, (d) more female, (e) more
diverse, (f) no worse academically, and (g) destabilized by
turnover (Ingersoll and Merrill 2010). Compared with the
BioScience 65: 812–821. © The Author(s) 2015. Published by Oxford University Press on behalf of the American Institute of Biological Sciences. All rights
reserved. For Permissions, please e-mail: [email protected].
doi:10.1093/biosci/biv093
Advance Access publication 22 July 2015
812 BioScience • August 2015 / Vol. 65 No. 8
http://bioscience.oxfordjournals.org
Education
entire teacher workforce, science and math teacher populations have grown significantly during this period (Ingersoll
and Merrill 2010) despite maintaining similar annual rates
of attrition (Ingersoll and May 2012). Short-term studies
of science and math teachers overcome the unwieldiness
of educational big data by focusing on a single SASS/TFS
year. With this approach, science and math teachers were
shown to leave the profession for different reasons, citing
maximum salary and classroom autonomy, respectively, in
2004–2005 (Ingersoll and May 2012). A drawback to this
large grain size, short-term approach is that stakeholders
are not clearly identified and informed of trends in their
­communities over time.
Small grain studies at the discipline level have the potential to identify stakeholder communities by focusing on an
educational issue. NCES technical reports contain numerous
data tables with teacher population information for a given
year and address issues such as race, gender, and course
information (e.g., see Bobbitt and McMillen 1994, Goldring
et al. 2013). Using short-term course data from 2008, large
equality gaps were identified between the percentage of
qualified chemistry and earth science teachers and the percentage of qualified biology teachers (Hill 2011). Examples
of longitudinal studies at the smaller grain size are limited.
We have recently described longitudinal trends in the high
school chemistry teacher population in order to illustrate
the features of a stakeholder community that might otherwise be masked by aggregation (Rushton et al. 2014). Our
analysis revealed that the number of chemistry teachers
has increased more rapidly than the number of remaining
STEM teachers but that approximately 70% of chemistry
teachers consistently do not report having earned a degree
in chemistry at any level. Furthermore, SASS data identified the qualified biology teacher population as a major
source of chemistry instructors that has not been thoroughly
described (Rushton et al. 2014).
Existing technical reports on the biology teacher population have taken a short-term approach, using the National
Survey of Science and Mathematics Education (NSSME)
and a smaller sample size than used in the SASS (Lyons
2013). Biology represents the most commonly offered high
school science subject (Banilower et al. 2013) and employs
more teachers than chemistry, earth science, and physics
combined (Hill 2011). Biology teachers are cited as more
than 60% female, although it is unclear from the reports
whether this represents a longitudinal trend warranting concern. Biology teachers are also more likely to teach multiple
subjects than other science teachers (Lyons 2013). Given
that biology teachers represent the largest group of science
teachers and are increasingly the disseminators of other high
school science subjects, we investigate populations teaching
US public high school biology and how they compare with
other STEM and non-STEM fields using SASS data from
1987–2007. Our fine grain, longitudinal approach explicitly
identifies the stakeholder communities who are best poised
to reflect on their current trends and initiate reform policies.
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Research Questions
(a) How many high school biology teachers are there in the
United States? What are the trends in population growth
compared with those of other teacher groups over the
past 20 years?
(b) What proportion of those who teach biology do so as
their main assignment? What other subjects do biology
teachers mainly teach?
(c) To what extent have high school biology teachers earned
biology or science education degrees at any level? What
other backgrounds do biology teachers have?
(d) What has been the certification status of biology teachers over time?
(e) To what extent has the racial and gender profile of
­biology teachers changed over time?
(f) To what extent have the age and years’ experience distributions changed over time?
Scope of the study
To address our research questions, we placed our study in
the context of labor market theory, which posits that attrition occurs after an employment agreement is made and
the quality of a match or alternate matches can be evaluated
(Jovanovic 1979, Murnane 1984). From the teaching or policy perspectives, respectively, understanding the educational
landscape influences the choice of teaching as a career match
or which candidates have matching skills and traits (Guarino
et al. 2006). We used the nationally representative SASS to
derive historic trends in the US teaching workforce, as we
previously described in our analysis of chemistry teachers (Rushton et al. 2014). Briefly, we used the six surveys
available from the following time periods: 1987–1988 (n =
17,960), 1990–1991 (n = 23,970), 1993–1994 (n = 24,630),
1999–2000 (n = 22,210), 2003–2004 (n = 23,110), and 2007–
2008 (n = 20,800), in which n is the unweighted number of
public high school teachers included in the sample. Our procedure was modified from Rushton and colleagues (2014) to
focus on biology teachers, to account for science education
degrees, and to update the STEM categories as explained in
greater detail in the online supplemental document available
on the BioScience Web site. We categorized teachers as biology, STEM, or non-STEM (all others) using distinct subject
codes provided in the SASS (table 1). We report weighted
values for teachers calculated in SAS version 9.3 software
using a specialized survey procedure that is designed to
account for the complex survey design and sample weights.
Biology dominates the science discipline within STEM education. We first examined the biology teacher workforce in the context of STEM education to better understand the national
emphasis on STEM education. Teachers with a main teaching assignment (i.e., a field in which they taught the most
classes) in STEM were first sorted into the component
disciplines of math, science, and technology/engineering
(figure 1a). In 2007, almost half (45%) of the STEM main
teaching assignments were occupied by math educators
August 2015 / Vol. 65 No. 8 • BioScience 813
Education
Table 1. STEM (science, techonology, engineering, and mathematics) teaching assignment options provided in the 2007
Schools and Staffing Survey (SASS) and used to group teachers for analysis.
Sciencea
Technology and Engineeringa,b
Matha,b
nonSTEMc
Biology/life sciences
Computer science
Algebra I
Art
Chemistryb
Industrial arts/technology education
Algebra II
Music
Earth sciencesb
Construction, engineering, science technology
Algebra III
Language Arts
Science, generalb
Drafting/graphics/printing
Basic and general math
Foreign languages
Physicsb
Communications and other technologies
Business and applied math
Social studies
Mechanics and repair
Calculus and precalculus
Physical education
Metals/woods/plastics precision production
Geometry
Economics
Library/information science
Prealgebra
Philosophy
Statistics and probability
Special education
Trigonometry
Other
Physical
sciencesb
Integrated scienceb
aDistinct
subjects included in the STEM category. bDistinct subjects included in the STEM excluding biology category. cSubjects included in the non-STEM category, shown as a subset of the approximately 50 distinct codes for illustrative purposes.
(i.e., 145,000 math educators). STEM main assignments
were also highly comprised of science educators (39%, or
125,000). The remaining main assignments (16%) were
filled by technology and engineering educators, who we
grouped together on the basis of variations in the SASS
survey language (e.g., the 2007 main assignment “construction trades, engineering, or science technologies (including
CADD and drafting)” could be classified as either technology or engineering). Similar proportions of all three STEM
disciplines were visible longitudinally between 1987 and
2007 (supplemental figure S1). The prevalence of science
and math main teaching assignments indicates that STEM
education in the US does not weigh each discipline equally,
as might be implied by an aggregated reform movement.
Furthermore, the relatively static distribution of main teaching assignments suggests that STEM reform has not resulted
in large-scale implementation of technology and engineering focused teachers in high schools. Our results are consistent with the 2005 finding that less than 7% of US high
school graduates completed science-technology or engineering courses (National Science Board 2008).
We also examined the biology teacher workforce in the
context of science education. Within the discipline of science, main teaching assignments have traditionally been
dominated by the biology subdiscipline (figure 1b). In 2007,
44% of science main teaching assignments were occupied
by biology educators, more than twice the percentage of
educators in chemistry, the second largest science population (20%). Comparable proportions of physical science
(9.4%), earth science (7.2%), and physics (7.1%) educators
occupied the third, fourth, and fifth largest science populations, respectively. Additional science educators accounting
for the balance of the main assignments (e.g., general and all
other sciences or else integrated sciences) were grouped as
general science. Over the 20-year sample period, a relatively
814 BioScience • August 2015 / Vol. 65 No. 8
static hierarchy for science main assignments has persisted,
suggesting that STEM reform efforts have not mobilized
other science teacher populations to challenge the monopoly
that biology holds over main assignments. Instead, the static
trends we observe align well with the hierarchy of bachelor degrees in biology (67%), chemistry (10%), physics
(4%), and earth science (3%) reported for the class of 2007
(National Science Board 2010).
Biology teacher growth rates outpace those in other STEM disciplines. The biology teacher population is reported to be three times
more likely than other sciences to teach three or more science
subjects (Lyons 2013). As a result, the entire biology teaching
population (i.e., those who teach one or more biology classes
or indicated a main assignment in biology) is anticipated to
be composed of more diverse instructors than are indicated
by main assignments. We examined the population growth
of biology teachers during the survey period and identified
53,600 biology teachers in 2007 ­(figure 2). Biology teachers
displayed sustained growth across the survey years, contrasting with the slower overall growth and periodic losses exhibited by STEM and non-STEM disciplines (figure 2). Biology
has grown most rapidly between 1999 and 2007, experiencing rates that were only recently mirrored by the 2003–2007
STEM growth (5.2% per year versus 4.7% per year, respectively). Using the class sizes reported by biology teachers and
the SASS weighting structure, we also calculated changes in
the number of biology students. After 1999, data indicate a
rapid increase in the student population, culminating in just
over 5 millions students in 2007 (figure 2). On the basis of
yearly fluctuations in the other teacher populations of less
than 6%, it appears that the trends in biology are likely to
persist and outpace STEM and non-STEM teacher growth.
Therefore, biology appears to benefit from its position as the
gateway science course in high school and is positioned to
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Education
a
Percent
100
80
Technology & Engineering
60
Science
40
Math
20
20
07
0
Year
b
Science
100
Physics
Physical Science
General Science
Earth Science
Chemistry
Biology
Percent
80
60
40
20
20
07
Year
20
03
19
99
19
93
19
90
19
87
0
Figure 1. The distribution of high school main teaching
assignments within STEM (science, techonology,
engineering, and mathematics) and science education.
(a) Percentage composition of the STEM disciplines
is shown for 2007 to illustrate the heavy emphasis on
math (45.1%) and science (39%) relative to technology/
engineering (15.9%). Standard errors for each discipline
are less than or equal to 0.98%. (b) Percentage composition
of the science discipline from (a) is shown by subdisciplines
between 1987 and 2007 to illustrate the dominance
of biology (across years average = 42.8%, standard
deviation [SD] = 1.6%) and chemistry (across years
average = 19.5%, SD = 1.4%) over the remaining natural
sciences, including physical science, which was added to
the Schools and Staffing Survey (SASS) in 1993. General
science includes other sciences in early surveys and is
manually aggregated with other or integrated sciences in
later years. Earth science and biology include geology
and life science, respectively. Standard errors for each
subdiscipline are less than or equal to 1.9%.
serve as the face of science for most students in the years to
come.
Biology teacher degrees and certifications are largely in-field. Biology teachers with a strong disciplinary background in
their field have previously been shown to increase student
achievement scores (Clotfelter et al. 2010). On the basis of
this rationale, we examined the disciplinary backgrounds
reported by the biology teacher workforce. We considered a
major degree in biology or life science at either the undergraduate or professional level to indicate a strong level of
http://bioscience.oxfordjournals.org
Figure 2. Percentage change in selected biology stakeholder
communities. Population growth relative to 1987 is
depicted for high school biology students (circles with solid
line), biology teachers (circles with dotted line), STEM
(science, techonology, engineering, and mathematics)
teachers excluding biology (squares with dashed line), and
the remaining non-STEM teachers (triangles with dashed
line). The data points represent percentage changes in the
weighted estimate values. Standard errors in the weighted
estimate values for teachers and students are less than or
equal to 6.5% in each year. The weighted estimate values
underlying the percentage change are shown for 2007 to
provide updated counts of each group.
training in disciplinary content, and we included degrees
conferred by both colleges of arts and sciences and colleges
of education in our analysis logic. Our analysis indicates that
the entire biology teacher workforce is composed of a high
percentage of in-field teachers (figure 3a). Between 1990 and
2007, in-field teachers rose approximately 14% to yield an
overall 65% chance that students would encounter a biology
teacher with a biology degree. The second most prevalent
degree held by biology teachers is physical education or
health education, which dominates the next most reported
degrees of science education and secondary education.
We recognize that some teachers included in the biology
teacher workforce (figure 3a) do not teach biology as their
primary subject and may not desire to hold a biology or
life science degree. By comparison, teachers who do teach
biology as a main assignment might be expected to hold a
greater proportion of degrees in biology and/or other natural sciences. An analysis of teachers with a main assignment
in biology shows a slight boost in the proportion of biology
degrees in each survey year (figure 3b). Between 1990 and
August 2015 / Vol. 65 No. 8 • BioScience 815
Education
1987
1990
1993
1999
2003
2007
70
60
Percent
50
40
a
100
nonSTEM
STEM
Bio
80
Percent
a
30
60
40
20
20
20
07
20
03
Year
Ed
b
Se
c
Sc
iE
d
PE
/H
ea
lth
Bi
ol
og
y
0
1987
1990
1993
1999
2003
2007
Degree
1987
1990
1993
1999
2003
2007
70
60
50
40
Percent
60
b
40
20
30
Degree
Figure 3. The distribution of the most prevalent degrees
held by biology teachers. (a) The entire biology teacher
workforce, including teachers who may only teach one
biology class. (b) Teachers with a main assignment in
biology (more than or equal to 50% of their course load),
illustrating a slight increase in reported biology or life
science degrees compared with panel (a). Standard errors
of the weighted estimates over the survey years in each
panel are (less than or equal to 2.7%).
2007, in-field teachers rose to approximately 70%, which
represents a 5% increase relative to the entire biology workforce. We found little variation in the next largest groups
of PE/health, science, and secondary-education degrees
relative to the entire biology teacher workforce (i.e., less
than or equal to 2.5% in each year, which is comparable to
the corresponding standard errors). Teachers with a main
assignment in biology also maintained a high proportion
(more than 83%) of in-field, regular certifications in biology (supplemental figure S2). Between 1987 and 2007, we
observe that the proportion of teachers reporting provisional
certifications is higher than those with no certification in
biology, consistent with novice teachers progressing toward
full certification status.
816 BioScience • August 2015 / Vol. 65 No. 8
at
Sc
ie
nc
e
Ea
rth
try
is
m
he
C
Ph
ys
ic
al
Sc
ie
nc
e
Ed
Se
c
Sc
iE
d
PE
/H
ea
lth
Bi
ol
og
y
0
h
**
0
10
M
20
G
en
er
al
Sc
ie
nc
e
Percent
19
99
19
93
19
87
19
90
0
10
Main Assignment
Figure 4. The distribution of biology teacher main
assignments. (a) The entire biology teacher workforce
is classified according to a teacher’s main assignment
to illustrate the recent decrease in non-STEM (science,
techonology, engineering, and mathematics) teachers
contributing to biology education, concomitant with an
increase in either biology or STEM teachers. Standard
errors over the survey years are less than 2.0%. (b) The
biology teachers with STEM main assignments from
panel (a) are disaggregated by STEM subject to show the
prevalence of general science over other popular STEM
content areas. Asterisks (*) denote populations that were
absent from the survey in a given year. Standard errors for
each discipline are less than 6.5%.
Biology teachers are decreasingly drawn from non-STEM main assignments. We further investigated the natural sciences as a
supplier of biology teachers by examining the main assignment fields that contribute teachers to biology classrooms.
First, we divided the entire biology teacher workforce into
the three main assignments of biology, STEM (excluding
biology), and non-STEM (figure 4a). Similar to our analysis
of degrees, biology teachers are predominantly drawn from
biology main assignments (across years average = 78.1,
standard deviation [SD] = 2.1%). Between 1987 and 1999,
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Education
the remaining main assignments that contributed biology
teachers were nearly equally shared between other STEM
and non-STEM disciplines (i.e., 0.1 to 1.5% differences in
each year). Longitudinal data indicate that only recently
have non-STEM disciplines decreased their contributions
to the biology teacher pool. Between 1999 and 2007, nonSTEM disciplines decreased almost twofold, from 11.3% to
6.3% respectively. As a result, the STEM-to-non-STEM gap
increased by approximately 5.4% in favor of biology teachers
from STEM main assignments.
On the basis of the declining contribution of non-STEM
teachers to biology classrooms, we focused next on the subdisciplines represented by the STEM category (figure 4b).
This STEM group represents only 2900–6600 teachers in
each survey year because of the more than fivefold excess of
biology main assignments. Still, we analyzed this group to be
thorough and to determine which STEM main assignments
contribute reduced course load biology teachers. We found
the majority of these biology teachers were drawn from main
assignments in general science, and this trend declined from
61% in 1987 to 32% in 2007. Following the inclusion of physical science on the 1999 survey, chemistry, earth science, and
physical science contributed statistically similar proportions
of teachers to biology classrooms (approximately 10%–30%).
Math main assignments represent the next most prevalent
(3%–12%) source of biology teachers (figure 4b), surpassing
the STEM fields of physics and industrial arts on average
(data not shown).
Decreases in classroom experience suggest instability in the biology teacher workforce. Given the high proportions of biology
teachers with in-field degrees or certifications and opportunities to teach mainly biology, it is tempting to hypothesize
that the biology teacher workforce may exhibit less turnover
relative to other disciplines. Biology teacher age and experience distributions reveal separate shifts toward younger
and less experienced teachers, respectively (supplemental
figure S3). Similar changes in chemistry teacher have previously been shown to derive from losses of older, experienced
teachers concomitant with an influx of not only younger,
novice teachers but also older, novice teachers (Rushton
et al. 2014). Therefore, we examined the longitudinal ageversus-experience profiles of biology teachers to understand
the causes of the increasingly inexperienced biology teacher
workforce (figure 5). We constructed a series of age-versusexperience brackets that were likely to be populated (e.g.,
teachers in their 20s with 0–5 years of experience), unlikely
to be populated (e.g., teachers in their 50s with only 0–5
years of experience), or impossible to be populated (e.g.,
teachers in their 20s with more than 16 years of experience).
For any given year, the anticipated diagonal exists in this plot
from upper left corner (novice, inexperienced teachers) to
lower right corner (older, experienced teachers). However,
if one examines the longitudinal detail provided in the ageversus-experience brackets, it is apparent that the proportion
of teachers with a given age and experience has not remained
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static over the survey period. Between 1990 and 2007, the
proportion of teachers in their 40s with 21–25 years of
experience decreased 20%, and teachers in their 50s with
more than 26 years of experience fell 27%. Attrition during
this period presented opportunities for novice teachers to
enter the profession. Although conventional wisdom might
suggest that these novice teachers would be young, we also
observe increases in the proportion of older, novice teachers.
Between 1990 and 2007, the proportion of teachers in their
40s or 50s with 0–5 years of experience each increased by
approximately 10%. The persistence of this trend in the 6–10
and 11–15 year experience brackets suggests that many of
these older, novice teachers remain in the profession.
Turnover in the biology teacher workforce favors underrepresented
groups. Next, we investigated how workforce hiring and
attrition affected the race and gender profile of biology
teachers (figure 6). In 1987, biology teaching was a maledominated (61%) profession, similar to other STEM teaching (­figure 6a). However, by 1999, biology teachers were
predominantly female (51%), ahead of the trend for the
remaining STEM population (only 46% female). Biology
continued a rapid increase in female teachers, reaching 61%
in 2007 and exceeding the gender equity seen in STEM
teachers. Biology appears to have plateaued at the comparable gender distribution of non-STEM teachers (61% female).
With respect to racial diversity, biology showed less deviation from the trends of other teacher groups (figure 6b). In
all groups examined, teaching is and remains a largely white
workforce at the national level. Between 1987 and 2007, the
biology teacher population reporting white alone decreased
4.7%, from approximately 91% to 86%. In contrast, the
distribution of teachers reporting black alone showed little
variation within the biology (across years average = 5.9,
SD = 1.1%), STEM (across years average = 6.5, SD = 0.5%),
and non-STEM (across years average = 6.8, SD = 0.5%)
groupings. As a result, gains in diversity in all teacher groups
were largely a product of teachers reporting other combinations (e.g., Asian or white–Hispanic). Biology exhibited a
4.9% increase in the racial category other, which was similar
to the increases in the STEM (4.9%) and non-STEM (5.2%)
teacher pools. Compared with the US adult population,
(biology) teachers are less diverse. In 2010, for example, the
US was 72.4% white alone, 12.6% black alone, and 15% other
combinations (US Census Bureau 2010).
Small grain size, longitudinal studies empower biology education
stakeholder communities. In the introduction, we highlighted
the importance of characterizing the educational landscape
that stakeholder communities are trying to shape. Previous
studies have addressed the entire—or just the science and
math—teacher populations but not the specific stakeholders who should act on those trends. Here, we have leveraged both the small grain size and longitudinal teacher data
that can be extracted from SASS data sets. We have used
this approach to disaggregate biology, the largest science
August 2015 / Vol. 65 No. 8 • BioScience 817
Education
Figure 5. Biology teacher age and experience shown as stacked bar charts to reveal trends in distinct age-versusexperience brackets across the survey years. The concentration of teachers along the upper left to lower right diagonal
is a consequence of the plot layout and improbability that, for example, teachers in their 20s have more than 15 years of
teaching experience. Relevant data are longitudinal trends within a given bracket. The solid-line boxes denote brackets
with decreasing trends and appear along the diagonal. The dashed-line boxes indicate brackets with increasing trends and
appear to the left of the diagonal. Axes correspond to the percentage of biology teachers (left y-axis) in a given age group
(right y-axis) with a given amount of teaching experience (upper x-axis) during the survey years (lower x-axis). Teachers
in each age group for a given survey year sum horizontally to 100%. Standard errors for weighted estimates of the teacher
populations are less than 7.8%.
subdiscipline (figure 1), so that communities (e.g., teacher,
professional-society, and higher-education groups) within
the aggregate STEM context can be informed of their own
story. Our data indicate that during the 20-year period
between 1987 and 2007, the American biology teacher workforce increased more than 50% in size; consisted of primarily
in-field, certified educators; remained predominantly white;
and became increasingly inexperienced and female. In this
section, we discuss these trends in the context of STEM
education reform and propose action steps for stakeholder
communities.
An examination of the degree programs from which biology teachers are drawn can inform efforts to improve the
quantity and quality of precollege educators in the profession. Although a majority of American biology teachers
reported having earned an in-field degree, the fact remains
that between one and two million biology students were in
classes not led by biology degree holders in 2007. When
818 BioScience • August 2015 / Vol. 65 No. 8
compared with other science teaching fields that historically have been populated by nonspecialists but are taught
to much smaller student populations, such as physics or
chemistry (Rushton et al. 2014), the impact of this out-offield biology teaching is comparable to or greater than any
other discipline. Two strategies that may address this condition are the concomitant efforts to increase the pipeline of
students in biological sciences degree programs that seek
teacher certification and to improve the content and pedagogical content knowledge of nonbiology degree–­holding
teachers (e.g., PE/Health; figure 3). The former has taken
shape in various national STEM teacher education initiatives
sponsored by corporations, private foundations, and federal
agencies, but none that we are aware of have specifically targeted those teaching biology (e.g., UTeach, SMTI, or Noyce).
Given the scope and diversity of careers, products, and
services connected to the study and knowledge of biological
sciences, there are likely a variety of potential sponsors to
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Education
a
100
Biology
STEM
nonSTEM
90
80
Percent
70
Female
Male
60
50
these organizations that promote dialogue between the various constituencies
that constitute the biology education
workforce could inform policy decisions
regarding programming, professional
support, and publication resources to
support the diverse needs represented
by biology teacher subgroups (e.g., those
mainly teaching physical sciences and
math; figure 4b).
40
Highly qualified biology teachers rapidly
become highly unqualified. The predomi-
30
20
19
8
19 7
9
19 0
93
19
9
20 9
0
20 3
07
19
8
19 7
9
19 0
93
19
9
20 9
0
20 3
07
19
8
19 7
9
19 0
9
19 3
9
20 9
0
20 3
07
nance of biology degree holders teaching biology as their main assignment
10
(figures 3 and 4) might lead to the con0
clusion that the organizational structure in schools is consistent with the
Year
ideal of appropriately supported science
education practices. Our data, however,
provide a richer context for findings
Biology
STEM
nonSTEM
100
from previous studies that suggest school
Other
staffing policies may not fully leverage
90
Black
the experience and interest of its employWhite
80
ees and therefore create difficult working
conditions (Ingersoll and Gruber 1996,
70
Hill 2011, Ingersoll and May 2012.)
60
Horizon Research’s recent report indi50
cated that biology teachers are more
likely than other science teachers to
40
teach three preparations (e.g., biology
30
and two other distinct classes) (Lyons
20
2013). On the basis of the large number
of biology teachers (figure 2) and their
10
disproportionately large hold on all sci0
ence teaching positions (figure 1), we
conclude that biology teachers are most
likely among all science teachers to teach
Year
outside of their discipline as part of their
Figure 6. Teacher workforce diversity in chemistry, STEM (science, techonology,
workload. That means a large proportion
engineering, and mathematics), and non-STEM disciplines. (a) Teacher gender
of teachers may become unqualified for
is depicted for each survey year, illustrating recent trends in an increasingly
some or most of the courses they teach
female teacher workforce. Standard errors for the weighted estimates of each
daily. Just as it was striking to see teachgender are less than 2.2%. (b) Teacher race is reported as white alone, black
ers with a main assignment in math stepalone, or other to show increased minority teachers in a predominantly white
ping into biology classrooms (figure 4b),
teacher population. Standard errors for the weighted estimates of each race are
biology teacher preparation is not anticiless than 1.8%.
pated to prepare teachers with pedagogical content knowledge for effective math
support such an enterprise. Following labor market theory,
instruction, for example. We also recognize the diversity of
scholarships or other employment incentives could target
science programs or degree tracks that would lead a teacher
high-quality undergraduate, graduate, or early-career degree
to select Biology or Life Science as a major in the SASS (figholders toward teaching positions while addressing the racial
ure 3). A microbiologist, for instance, may feel unprepared
homogeneity in biology teaching (figure 6b). Regarding the
to teach AP environmental science or an elective in human
empowerment of the out-of-field biology teachers, targeted
anatomy and physiology for the first time. In this respect, the
professional development by state or national biology or
math teacher and “highly qualified” biology teacher teaching
science teacher associations may be fruitful. Task forces in
far in-field may both experience the decreased self-efficacy
19
8
19 7
9
19 0
9
19 3
9
20 9
0
20 3
07
19
8
19 7
9
19 0
9
19 3
9
20 9
0
20 3
07
19
8
19 7
9
19 0
93
19
9
20 9
03
20
07
Percent
Percent
b
http://bioscience.oxfordjournals.org
August 2015 / Vol. 65 No. 8 • BioScience 819
Education
and sense of professional identity associated with teaching
out-of-field (Ingersoll and Gruber 1996, Hobbs 2013).
For biology teachers, whether stepping in from a non–life
science discipline or stepping outside their content area,
in-field certification remains high (supplemental figure S2).
As a result, biology teachers are often tasked with teaching
courses for which they are certified but in which they may
not have sufficient preparation to develop self-efficacy. The
out-of-field biology teacher can struggle with self-efficacy
because of a perceived lack of content knowledge in the field.
Alternatively, teachers without experience in how to facilitate the conceptual understanding of fundamental concepts
and ideas can develop low self-efficacy from a perceived
lack of pedagogical content knowledge. Depending on the
intensity and frequency with which these sources of low selfefficacy are experienced by the out-of-field biology teacher,
negative emotions can impinge on their professional identity
and cause enough discomfort to warrant the reevaluation of
their choice of employment location (i.e., school or district)
or even the vocation itself (Cherniss 1996, Chang 2009,
Kukla-Acevedo 2009).
The self-appraisal of negative emotions and how far
out-of-field a teacher falls can be negotiated according to
whether the biology teacher perceives their professional
identity as teacher (with a background in biology) or biologist
(in a teacher role). Our age-versus-experience data show that
older biology teachers with more life experience are entering
the workforce (figure 5). For those teaching after a career in
their disciplinary field, the biologist identity may be s­ tronger
than that of teacher. Therefore, an assignment to teach
­outside their field may negatively influence self-efficacy to a
greater extent than for those who identify as teacher first and
with subject secondarily (Skaalvik and Skaalvik 2010). For
the teacher identity, uncertainty in content or context may be
perceived as challenges inherent in the profession, which can
be overcome by a knowledge of general pedagogy, an ethic of
care, and a confidence in learning new ideas to support their
students. In summary, the observation that biology teachers are often assigned to subjects outside of biology may or
may not be a cause for concern. In cases in which there is a
significant incongruence between the teaching assignment
and the teacher’s professional identity, it is more likely that
access to a quality science education experience may be
affected; in cases in which the incongruence is small, then
possibly less so.
courses at each school, district, or county, the curriculum is
chosen largely as a function of the expertise of those teachers who they employ. An example might be a school that has
historically offered a course in anatomy and physiology and
has assigned teachers with biology certifications to teach it
regardless of the emphasis of their degree program, such as
marine ecology or chemistry. Instead of placing a teacher
with an in-field certification but out-of-field background in
those settings, we propose that the curricular choices should
be made once the teaching positions have been secured and
finalized for the next academic term. As a result, zoology or
biochemistry, respectively, might be taught instead of human
anatomy. We recognize that this solution is accompanied by
other competing logistical and philosophical considerations
but places the priority on supporting an alignment between
teacher quality and student course enrollment rather than
on the current staffing policy structure that supports frequent mismatches between the two.
Additional studies of the biology teacher workforce could
provide additional context for policy decisions that affect
this professional community. We noted, for example, a concomitant shift from male dominant to female dominant with
an increasingly inexperienced American biology teacher.
Is this merely coincidental, or is there a causal relationship
that exists, and what implications does that have for scienceeducation efforts? Have certain geographic areas shifted
more drastically toward a particular demographic profile
compared with others, and is there any correlation to student
achievement outcomes? Answers to these questions are currently being investigated as additional SASS surveys become
available and are intended to better equip all stakeholder
communities with data to make informed decisions regarding their goals and objectives.
Conclusions
Many suggestions for improving science education have
been discussed in terms of more stringent certifications
and targeted professional development for teachers in the
subjects they have been assigned (see Ingersoll 2001).
Instead, we support an alternative at the organizational level
of school staffing structures that would better leverage the
diverse talents and interests of the biology teachers from second careers and in-field and out-of-field degree programs.
Instead of offering a static, predetermined slate of science
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820 BioScience • August 2015 / Vol. 65 No. 8
Acknowledgments
This work was supported in part by National Science
Foundation Award no. DUE-1035451. The authors would
also like to gratefully acknowledge the financial support from
Kennesaw State University, as well as our colleagues providing valuable feedback on early drafts of this manuscript.
Supplemental material
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Samuel J. Polizzi is a postdoctoral associate at Kennesaw State University, in
Georgia. His research focuses on teacher induction, leadership development,
and biochemistry education. Jeremy Jaggernauth studied applied statistics
in the Department of Statistics and Analytical Sciences at Kennesaw State
University. He is currently employed as a statistical analyst in the private sector. Herman E. Ray is an assistant professor of statistics in the Department of
Statistics and Analytical Sciences at Kennesaw State University. His research
focuses on the analysis of large, complex data sets in health care and education
as well as multivariate clinical trial designs. Brendan Callahan is an assistant
professor of biology education in the Department of Biology and Physics at
Kennesaw State University. His research focuses on the influence of moral
and ethical issues on secondary science to develop literacy and critical thinking. Gregory T. Rushton ([email protected]) is an associate professor
of chemistry at Kennesaw State University. His research interests lie at the
intersection of secondary and tertiary science education and in developing
science teacher leaders.
August 2015 / Vol. 65 No. 8 • BioScience 821