ILTS Science: Biology (239)
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Cheat sheet
Keep the key ideas within reach.
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Get comfortable with the vocabulary.
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Give each week a clear focus.
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Understand the traps and how to avoid them.
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Put your knowledge to work in context.
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ExploreAbout this exam
Science: Biology (239) is one of the content-area tests listed in the Illinois Licensure Testing System (ILTS) catalog, published on the ILTS site at il.nesinc.com. It sits alongside Science: Chemistry (240), Science: Earth and Space Science (241), Science: Environmental Science (242), and Science: Physics (243) as a single-subject science assessment, and it is intended for candidates seeking an Illinois educator license with a biology endorsement. The ILTS program is administered for the Illinois State Board of Education, but this page is independent study material and is not affiliated with ILTS, Pearson, or the State of Illinois. The public catalog does not publish a subdomain breakdown, item count, or time limit for this title, so build your preparation around the biology content that a secondary biology teacher is expected to teach: molecules and cells, genetics and evolution, organisms and populations, and the nature and practice of scientific inquiry, including data analysis and experimental design. Start by confirming the current test requirements and available preparation materials through the official ILTS website. Then work through practice questions under timed conditions, review every miss down to the underlying concept, and revisit the topics you cannot explain aloud. Registration fees were reduced for all ILTS test titles as of 1/28/2025, and practice tests are now provided automatically during registration where a corresponding practice test exists.
What you'll study
About ILTS Science: Biology (239) preparation
What is the Science: Biology (239) test for?
It is an ILTS content-area assessment for candidates seeking an Illinois educator license with a biology endorsement. It appears in the ILTS test catalog alongside the other single-subject science tests (Chemistry 240, Earth and Space Science 241, Environmental Science 242, Physics 243). Confirm your specific program requirements on the official ILTS site before registering.
What does the exam cover?
The public ILTS catalog does not publish an official subdomain breakdown for this title, so no weightings can be quoted. Prepare broadly across the biology a secondary teacher must teach: molecular and cellular biology, genetics, evolution, organismal and population biology, ecology, and scientific inquiry, including experimental design and data interpretation.
How many questions are on the test, and how long is it?
The source does not state an item count or a time limit for Science: Biology (239). Treat any specific number you see elsewhere as unverified. Check the official ILTS test page for your title for the authoritative format information before you plan your pacing strategy.
How much does it cost, and can I retake it for free?
Registration fees were reduced for all ILTS test titles as of 1/28/2025, but the current amount for this title is not stated in the source. Separately, ILTS examinees with two unsuccessful attempts may be eligible to retake the same test at no cost. Verify both the fee and your eligibility on the official site.
Do I get a practice test when I register?
As of 1/28/2025, practice tests are provided automatically during registration for tests for which the corresponding practice test is available at the time of registration. Availability is test-specific, so confirm whether a practice test exists for Science: Biology (239) rather than assuming one is included.
How difficult is it, and what trips candidates up?
The catalog publishes no pass rates, so difficulty cannot be quantified here. The most common self-inflicted problems are studying only vocabulary, skipping quantitative genetics and data-analysis practice, and never working under time pressure. Practicing application-level questions and reviewing every error to its root concept is more effective than rereading notes.
In what order should I study?
Begin with a diagnostic set of practice questions to find weak areas, then study content by cluster: molecules and cells, genetics and evolution, then organisms, populations, and ecology. Finish with inquiry and data-analysis practice, which appears across all areas. Re-test weak clusters after a gap to confirm retention rather than momentary recognition.
Where do I find test dates, sites, and registration?
The ILTS website provides test dates and sites, online registration, preparation materials, alternative testing arrangements, and testing policies. Use the official site as your single source for scheduling and policy questions, since fees, announcements, and practice-test availability change over time.