The California Science Test (CAST) at Grade 8 is the bridge between middle-school NGSS and high-school NGSS — cumulative across grades 6-8, 59 Performance Expectations, the last CAST before the high-school administration. 32.66% of California students are proficient.
Grade 8 CAST is the bridge from middle-school NGSS to high-school NGSS. It is the second of three operational CAST administrations (Grade 5, Grade 8, and once in high school at Grade 10, 11, or 12). At Grade 8, the test is built against 59 NGSS Performance Expectations spanning the grades 6-8 standards — three full years of middle-school NGSS, with phenomena that integrate Physical Sciences, Life Sciences, Earth & Space Sciences, and Engineering/Tech/Applications. Like all CAST administrations, every item is three-dimensional (Disciplinary Core Idea + Science & Engineering Practice + Crosscutting Concept) and presents a real-world phenomenon — a graph of a chemical reaction over time, a model of plate tectonics, a setup with Newton's-laws data — rather than asking abstract recall.
The Grade 8 content peak is conceptually demanding: chemical reactions (rearrangement of atoms, conservation of mass), Newton's laws of motion, forces between objects, kinetic and potential energy, waves (sound, light, electromagnetic spectrum), photosynthesis vs. cellular respiration at the molecular level, inheritance and variation of traits, natural selection, the solar system, plate tectonics, human impacts on Earth systems (climate, biodiversity loss), and engineering design including iteration on a competing-solutions trade-off analysis. Items routinely combine domains — a 'design a water filter' item integrates Life Sciences (what organisms need clean water) with Engineering (design criteria) with Physical Sciences (properties of materials).
32.66% of California students scored Met or Exceeded Standard on the 2024-25 CAST (all grades combined), per the CAASPP-ELPAC dashboard. Grade 8 specific data is gated behind a dropdown on the dashboard — the all-grades figure is the best available public anchor. CAST is computer-delivered but NOT computer-adaptive (a common misconception) — it is a linear fixed-form test with embedded equating items. Two segments: a Discrete segment of stand-alone three-dimensional items, and a Performance Task segment with 4-6 connected items including one hand-scored 2-point constructed-response item. Total ~50 items plus PT cluster. Untimed; CDE estimates about 2 hours.
CAASPP uses 4 achievement levels. As of the 2024-25 score reports (October 2025), the California State Board of Education renamed them: Minimal (formerly Standard Not Met), Developing (formerly Standard Nearly Met), Proficient (formerly Standard Met), and Advanced (formerly Standard Exceeded). Cut scores did not change. Proficient is the federal 'on grade level' target. Each grade has its own scale-score range; SBAC scores are vertically scaled across grades, while CAST scores are not.
Statewide CAST aggregate for grades 5, 8, and HS combined — up 1.96 ppt from 2023-24, the largest of the three CAASPP subjects' year-over-year gains. Grade 8 specific data is gated behind a dropdown on the CAASPP-ELPAC dashboard.
Source: CAASPP-ELPAC CAST Dashboard 2024-25, caaspp-elpac.ets.org/caaspp/DashViewReportCAST
Real CAST format. Aligned to California Next Generation Science Standards (CA NGSS). Detailed explanations on every answer.
CAST reports against three dimensions rather than reporting categories the way SBAC does. Every CAST item integrates a Disciplinary Core Idea (the science content), a Science & Engineering Practice (the practice), and a Crosscutting Concept (the connecting lens). The Disciplinary Core Ideas span four domains, which serve as the closest analog to SBAC's reporting categories. Grade 8 phenomena are more conceptually demanding than Grade 5 — chemical reactions, Newton's laws, photosynthesis at the molecular level.
| Reporting Category | What's Tested |
|---|---|
| Disciplinary Core Idea: Physical Sciences (PS) | Chemical reactions (rearrangement of atoms, conservation of mass), Newton's laws of motion, forces between objects, kinetic and potential energy, waves (sound, light, electromagnetic spectrum). The conservation-of-mass concept (started at Grade 5) reaches its peak conceptual demand here. |
| Disciplinary Core Idea: Life Sciences (LS) | Structure and function (cells, body systems), inheritance and variation of traits, natural selection, ecosystems and biodiversity, photosynthesis vs. cellular respiration AT THE MOLECULAR LEVEL — a major Grade 8 escalation. |
| Disciplinary Core Idea: Earth & Space Sciences (ESS) | The solar system, plate tectonics, Earth's resources and natural hazards, human impacts on Earth systems (climate change, biodiversity loss). Plate tectonics is a defining Grade 8 topic. |
| Disciplinary Core Idea: Engineering, Technology & Applications of Science (ETS) | Define design criteria, evaluate competing solutions, iterate on a design. At Grade 8, engineering items often integrate with another DCI — design a water filter (LS + ETS), model an earthquake-resistant building (ESS + ETS). |
| Science & Engineering Practices (SEP) — 8 practices integrated into every item | Asking questions, developing and using models, planning and carrying out investigations, analyzing and interpreting data, using mathematics and computational thinking, constructing explanations and designing solutions, engaging in argument from evidence, obtaining and communicating information. |
| Crosscutting Concepts (CCC) — 7 connecting lenses | Patterns, cause and effect, scale/proportion/quantity, systems and system models, energy and matter, structure and function, stability and change. Every item carries a CCC label. |
Grade 8 CAST is the bridge between middle-school NGSS and high-school NGSS. It is the second of three operational CAST administrations (Grade 5, Grade 8, and once in high school) and the last CAST before California high schools transition into the NGSS course sequence — typically Living Earth in Grade 9, Chemistry in the Earth System in Grade 10, and Physics of the Universe in Grade 11. The Grade 8 test is built against 59 NGSS Performance Expectations spanning the grades 6-8 standards — three full years of middle-school NGSS, with phenomena that integrate Physical Sciences, Life Sciences, Earth & Space Sciences, and Engineering. The content is conceptually demanding: chemical reactions with conservation of mass, Newton's laws, photosynthesis at the molecular level, plate tectonics, natural selection, human impacts on climate. Like every CAST administration, items are phenomena-based and three-dimensional — they ask students to analyze, explain, or evaluate, never to recite. For families, two key things to know. First, Grade 8 CAST scores are NOT comparable to Grade 5 CAST scores — each grade uses a separate score band (G5: 150-250; G8: 350-450). Second, while CAST scores typically don't drive direct high-school course placement, the score report's domain-level breakdown is the most useful diagnostic available before high-school NGSS courses begin — it tells you which Disciplinary Core Idea your child should strengthen over the summer.
Drill the three dimensions habit. Every CAST item integrates a Disciplinary Core Idea (the content), a Science & Engineering Practice (the practice), and a Crosscutting Concept (the lens). On practice items, ask 'What science content (DCI) is this? What scientific practice (SEP) is the question asking — analyze data, build a model, construct an explanation? What crosscutting concept (CCC) connects it — patterns, cause-and-effect, energy & matter, systems?' This metacognitive habit transfers directly to CAST items.
Photosynthesis and cellular respiration at the molecular level is a high-leverage Grade 8 topic. Most students remember 'plants make food using sunlight' from elementary but lose track at the molecular level (CO2 + H2O + sunlight → glucose + O2, and the reverse for cellular respiration). Practice the equations and the conservation of atoms — where does each atom come from, where does it go?
Plate tectonics is a defining Grade 8 Earth Science topic. Practice with real-world phenomena: why do earthquakes cluster at plate boundaries? Why does the Pacific Ring of Fire exist? Why are the Himalayas still growing? The 'why' questions are the exact CAST item style; the 'where' questions are recall and won't show up on the test.
Use the free CDE Practice Tests and Tools for Teachers at caaspp-elpac.org. CAST has its own released-item set with the interactive simulation tools the real test uses. 30-45 minutes of interface familiarization is the cheapest test-prep intervention available.
Don't cram. CAST Grade 8 content spans grades 6-8 NGSS — three full years. A month of cramming won't cover it. Six months of weekly review beats a March cram. One Disciplinary Core Idea per week through the school year covers everything: chemical reactions, Newton's laws, energy, waves, cells, ecosystems, heredity, evolution, the solar system, plate tectonics, Earth's resources, human impacts. Real-world examples (current news on earthquakes, biodiversity, energy) anchor the content far better than abstract diagrams.
59 NGSS Performance Expectations spanning grades 6-8, across four Disciplinary Core Idea domains: Physical Sciences (chemical reactions, Newton's laws, forces, energy, waves), Life Sciences (cells and body systems, inheritance, natural selection, photosynthesis at molecular level), Earth & Space Sciences (solar system, plate tectonics, Earth's resources, human impacts on climate), and Engineering/Tech/Applications (define criteria, evaluate competing solutions, iterate on design). Every item integrates a Disciplinary Core Idea, a Science & Engineering Practice, and a Crosscutting Concept.
CDE estimates about 2 hours total. The test is officially untimed in California — students may take as long as the school day allows. Most districts administer CAST in one or two sessions during the CAASPP window (typically March-May, alongside the SBAC ELA and Math tests).
Yes — CAST is fully NGSS-aligned. California adopted the Next Generation Science Standards in 2013, and CAST replaced the older California Standards Test (CST) for Science (which was based on the 1998 science standards). CAST became operational statewide in spring 2018 after a multi-year pilot. Every CAST item is written against one of 175 NGSS Performance Expectations: 45 at Grade 5, 59 at Grade 8, and 71 at high school.
Anchor phenomena typical at Grade 8: chemical reactions involving conservation of mass (Physical), Newton's laws applied to forces between objects (Physical), photosynthesis and cellular respiration at the molecular level (Life — a defining Grade 8 escalation), natural selection and inheritance of traits (Life), plate tectonics and Earth's surface (Earth), human impacts on climate and biodiversity (Earth + Engineering), and engineering-design problems that often integrate two or three domains.
The all-grades statewide rate for 2024-25 was 32.66% Met or Exceeded Standard, per the CAASPP-ELPAC dashboard. Grade 8 specific data is gated behind a dropdown on the dashboard and runs in roughly the same band. CAST proficiency moved up 1.96 percentage points statewide from 2023-24 — the largest of the three CAASPP subjects' year-over-year gains. For your child's specific grade-8 rate, check the official CDE dashboard.
Generally not directly — California high-school science placement is set by individual districts and most rely on Grade 8 SBAC scores (especially Math) plus teacher recommendation. CAST scores feed into the California School Dashboard for school-level accountability, not student-level placement. That said, a Grade 8 CAST score is a useful diagnostic before the high-school NGSS courses (typically Living Earth in Grade 9, Chemistry in the Earth System in Grade 10, Physics of the Universe in Grade 11) — it tells you which Disciplinary Core Idea domain needs strengthening before high school.
A phenomenon is an observable event in the natural world that the student must explain or predict using science. Examples on the Grade 8 CAST: a chemical reaction with a measurable change in mass — does the mass actually change or is it conserved? A graph of a plant's growth and oxygen production — how does the plant gain mass? A model of plate movement — what causes earthquakes at the boundary? CAST items present a phenomenon and ask students to analyze data, build a model, or construct an explanation — not 'What's the chemical formula for glucose?'
Computer-based. CAST is administered exclusively on the ETS-built CAASPP delivery platform — the same interface used for SBAC ELA and Math. Paper administration is available only as an accommodation for students with documented needs. The test interface includes interactive simulations, on-screen data analysis tools, drag-and-drop, hot text, and a constructed-response typing interface.
CAST is scored on a scale from 350 to 450 for Grade 8. Four achievement levels (using the new 2025 labels): Minimal (was Standard Not Met, 350-377), Developing (was Standard Nearly Met, 378-414), Proficient (was Standard Met, 415-432), and Advanced (was Standard Exceeded, 433-450). Proficient is the federal 'on grade level' target. The score report shows the achievement level and the scale score, plus a breakdown by science domain. Important: Grade 8 CAST scores are NOT comparable to Grade 5 CAST scores — each grade uses a separate score band.
California parents can opt their child out of state assessments by submitting a written request to the school. Schools must honor it; the student gets an alternate productive activity during testing. However, opting out doesn't change the federal 95% participation requirement, so districts often discourage opt-outs. CAST is the only statewide science assessment between Grade 5 and high school — opting out means losing the only NGSS-aligned middle-school signal before high-school science begins.
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