TExES 238 Exam Domains 2026: Complete Guide to All 6 Content Areas

Exam Overview: How the Six Domains Fit Together

The TExES Life Science 7-12 (238) exam is organized around a 2019 content framework that defines 20 competencies distributed across six domains. These domains map directly to Life Science 7-12 Standards I-XI and to the Texas Essential Knowledge and Skills (TEKS) that Texas secondary science teachers are expected to deliver in the classroom. Understanding how the domains are weighted - and what topics live inside each one - is the single most efficient way to plan your preparation, because it tells you exactly where to spend your limited study hours.

Unlike a generic science certification, TExES 238 is administered by Pearson (Evaluation Systems) on behalf of the Texas Education Agency and the State Board for Educator Certification. It's a computer-administered test delivered at Pearson VUE centers, and every question you see is tied to one of these six domains. This guide breaks down each domain in detail so you know precisely what to expect on test day. For a broader look at how to structure your entire preparation, pair this guide with our TExES 238 Study Guide 2026.

Domain 1: Scientific Inquiry and Processes (15%)

This domain tests whether you understand how science actually works - not just what scientists have discovered, but how they investigate, measure, and reason through uncertainty. Expect items on experimental design, variable control, data interpretation, laboratory safety, and the appropriate use of tools and measurement in a life science classroom context.

Because no calculator or formula sheet is provided, you need to be comfortable reasoning through simple data sets and proportional relationships mentally or on scratch material provided at the testing center.

Domain 2: Cell Structure and Processes (20%)

This is one of three domains tied for the exam's heaviest weight, and it's foundational to nearly everything else tested. You'll need deep, functional knowledge of cell biology - not just memorized vocabulary, but the ability to explain mechanisms and predict outcomes when conditions change.

Domain 3: Heredity and Evolution of Life (20%)

The second of the three heavily weighted domains, this section blends classical genetics with modern molecular biology and evolutionary theory. You should expect questions that require you to trace inheritance patterns, interpret molecular evidence, and explain evolutionary mechanisms with precision.

Because this domain draws on both classical and molecular genetics, candidates who studied biology years ago often need a refresher on newer molecular techniques and how they're used as evidence for evolutionary claims. If you're unsure how heavily this content is tested relative to your comfort level, our TExES 238 difficulty guide breaks down where most candidates struggle.

Domain 4: Diversity of Life (20%)

The third domain sharing the top 20% weighting, Diversity of Life asks you to demonstrate breadth across taxonomy and organismal biology. This is where the exam moves from molecules and mechanisms to whole organisms and how they're classified, structured, and behave.

Because Domain 2, Domain 3, and Domain 4 collectively make up roughly 60 of the 100 scored questions, mastering these three domains should be the backbone of your preparation timeline. Together they represent the difference between a marginal pass and a comfortable one.

Domain 5: Interdependence of Life and Environmental Systems (15%)

This domain zooms out from individual organisms to ecosystems, populations, and the relationships between living things and their environment. Expect questions on energy flow, nutrient cycling, population dynamics, and human impact on natural systems.

Domain 6: Science Learning, Instruction and Assessment (10%)

The smallest domain by weight, but not one to skip. This section tests pedagogical knowledge specific to teaching life science: how students learn scientific concepts, how to design effective instruction, and how to assess understanding fairly and accurately.

Even at 10%, this domain can be the difference-maker for candidates who are strong on content but rusty on instructional theory. Remember that passing TExES 238 is only one certification step - a first Texas classroom certificate also requires passing the PPR EC-12 (160) pedagogy exam, so building strong instructional reasoning now pays off twice.

Why the "Big Three" Domains Deserve Extra Attention

With three domains tied at 20% each, roughly 60% of your exam questions come from Cell Structure and Processes, Heredity and Evolution of Life, and Diversity of Life. The remaining 40% is split among Scientific Inquiry (15%), Interdependence of Life and Environmental Systems (15%), and Science Learning, Instruction and Assessment (10%).

This weighting explains a lot about why the exam has proven challenging for many candidates. Understanding exactly where the score-bearing questions concentrate is one of the reasons we built a full breakdown of statewide performance in our TExES 238 pass rate analysis, and why the passing score itself deserves its own deep dive in our passing score guide.

Building a Domain-Based Study Timeline

Rather than studying topics in the order they appear in a textbook, align your preparation schedule with domain weight. Spend the most calendar time on the three 20% domains, moderate time on the two 15% domains, and a lighter but non-zero block on the 10% instructional domain.

If you need a condensed reference to keep nearby during final review, our TExES 238 Cheat Sheet distills the must-know facts from every domain onto one page.

Question Format and Registration Mechanics

Knowing the content domains matters, but so does knowing the mechanics of the test day itself. TExES 238 consists of 100 selected-response questions, some of which are unscored field-test items used to evaluate future exam content - only the scored questions count toward your final scaled score, so treat every item as if it counts.

You must be approved to test by an educator preparation program or by TEA before you can register, and scores post at 10:00 p.m. Central on the published score report date. If you don't pass on your first attempt, you're allowed up to five total attempts with a required 30-day wait between each; a TEA test-limit waiver is needed if you need to go beyond five. For a full walkthrough of eligibility steps, see TExES 238 Requirements 2026, and for a breakdown of every fee involved, check TExES 238 Certification Cost 2026.

Because the domain content is dense and the passing bar (240 on a 100-300 scale) requires consistent performance rather than excelling in just one area, most successful candidates combine domain-specific review with realistic timed practice on our full-length TExES 238 practice tests well before their scheduled appointment.

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