Subject Knowledge and Its Discontents: What Teachers Know About What They Teach

Subject Knowledge and Its Discontents: What the Evidence Shows About Teacher Content Knowledge

A contributing voice from policy analysis | Specialist in education equity, school improvement, and teacher professional development

The research on teacher subject knowledge and student outcomes is genuinely unambiguous on one point: it matters, and gaps in it are more common than the system’s credentialing structure suggests. CTET’s 2026 results make this concrete rather than abstract — only 25.68% of candidates qualified, despite every one of them already holding the B.Ed. or D.El.Ed. degree required to sit the exam in the first place. That gap between formal qualification and demonstrated competence is the actual problem this piece is about, and the evidence on what closes it is more specific than “more training.”

Key facts

• CTET 2026 results showed only 25.68% of candidates qualified, despite all test-takers already meeting NCTE degree eligibility requirements — a stark, current indicator that formal teacher-training credentials do not reliably translate into demonstrated subject and pedagogical competence.
• State-level Teacher Eligibility Test pass rates run as low as 10-20% in states like Karnataka.
• UDISE+ 2024-25 data found 12% of India’s teachers — roughly 1.2 million people — lack professional qualifications altogether.
• A rigorous value-added study (Kingdon & Azam, 2015) found a one-standard-deviation improvement in teacher quality raises student scores by 0.366-0.476 standard deviations over two years — a substantial, real effect. Critically, the same research found that observable traits — degrees, formal training, years of experience — do not fully explain this quality variation, meaning credentials alone are an incomplete proxy for what actually drives classroom effectiveness.
• The Supreme Court of India, in a September 2025 ruling, mandated TET certification for all in-service primary and upper-primary teachers, including those hired before 2011 under older norms — affecting an estimated 20-30 lakh teachers nationally, with a two-year grace period running to 2027.

Credentials matter, but they’re not the whole answer — and the evidence is specific about why

A quarter of already-degree-holding candidates passing CTET is not a story about untrained people entering teaching. It’s a story about degrees that don’t reliably certify the subject and pedagogical knowledge they’re supposed to represent — which means the fix has to be more specific than “require more credentials.”

This is the honest complication worth stating plainly. Kingdon and Azam’s research found real, large teacher-quality effects on student outcomes — but also found that the credentials the system currently uses to sort and hire teachers don’t fully capture that quality variation. That’s not an argument against TET or qualification requirements; the Supreme Court’s 2025 ruling reinforcing TET as mandatory reflects a genuine legal and quality floor. It is an argument that a credential alone — pass the exam, get the degree — is a necessary but insufficient response to a problem that is ultimately about ongoing content knowledge, not one-time certification status.

Five principles for addressing subject-knowledge gaps specifically

1. Diagnose whether the gap is content knowledge, pedagogy, or both, for specific teachers and subjects. TET tests both content and pedagogy together; a school responding to low performance needs to know which specific dimension is driving it before choosing a professional development response.
2. Build peer and mentoring relationships that can catch what credentials miss. Since Kingdon and Azam found observable qualifications don’t fully explain quality variation, informal, relationship-based knowledge-sharing between colleagues may surface and address gaps a formal credentialing process does not capture.
3. Treat subject-knowledge development as ongoing, not a one-time gatekeeping exam. TET is designed as an eligibility filter at hiring, not a continuous development mechanism — a school waiting for the credentialing system to solve this on its own is relying on a tool built for a different purpose.
4. Bring in subject-matter partners rather than assuming general training suffices. Organisations like Azim Premji Foundation and NCERT publish subject-specific professional development resources that target content knowledge directly, rather than the general pedagogical training most in-service programmes emphasise.
5. Start with what’s diagnosable now, without waiting for the 2027 TET deadline to resolve staffing. A school does not need every teacher TET-certified to begin identifying specific content gaps through existing formative assessment and classroom observation — the compliance deadline and the diagnostic work are separate timelines.

Frequently asked questions

How common are subject-knowledge gaps among Indian teachers, in concrete terms? Substantial by the clearest available measure: CTET 2026 saw only 25.68% of already-degree-holding candidates qualify, state-level TET pass rates run as low as 10-20% in some states, and UDISE+ 2024-25 data found 12% of all teachers nationally lack professional qualifications entirely.

Does requiring more credentials — like the Supreme Court’s TET mandate — actually fix the underlying problem? Partially. TET serves a real legal and quality-floor function, and the Supreme Court’s 2025 ruling extends that floor to teachers hired before 2011. But the same research establishing that teacher quality matters (Kingdon & Azam) also found observable credentials don’t fully explain quality variation — meaning credentialing alone is necessary but not sufficient.

What does rigorous research say the actual size of the teacher-quality effect is? Large: a one-standard-deviation improvement in teacher quality was found to raise student scores by 0.366-0.476 standard deviations over two years — a substantial, well-evidenced effect, even though the same research shows this quality isn’t fully captured by formal qualifications.

What can a school do given the Supreme Court’s ruling and its 2027 compliance deadline? The compliance timeline and the diagnostic work don’t have to wait on each other — a school can identify specific content-knowledge gaps by subject and grade using existing formative assessment now, rather than treating TET certification as the sole mechanism for addressing subject-knowledge quality.

What to do:

1. Identify, by subject and grade, where your school’s specific content-knowledge gaps actually are, rather than assuming credential status alone tells you.
2. Speak with one colleague who demonstrates strong subject mastery in an area where others struggle, and ask specifically how they built that depth.
3. Read Kingdon & Azam’s research or NCERT/Azim Premji Foundation’s subject-specific professional development resources, and share one specific finding with your headmaster this week.
4. Propose one concrete, subject-targeted professional development step — not a general training session — for the specific gap you’ve identified.
5. Set a review date four weeks out to check whether the targeted support made an observable difference, and write it down today.

Sources: “CTET Results 2026,” Education For All in India (April 2026); “Supreme Court’s TET Mandate,” Education For All in India (September 2025), citing UDISE+ 2024-25 and ASER 2023 data; Kingdon, G., & Azam, M. (2015), “Assessing Teacher Quality in India,” Journal of Development Economics.