OpenLab Science vs. PhET Interactive Simulations

PhET is the category default for free physics simulations — a well-earned reputation built on 174 simulations, a strong accessibility program, and more language translations than any other product compared on this site. In 2025 it also launched PhET Studio, a paid preset platform that by design collects no student work. This page is not an argument that PhET is worse. It is a specific answer to a specific question: what does OpenLab add for a teacher who already knows and likely already uses PhET?

Curriculum & standards coverage

Named framework coverage

• OpenLab Science (Yes): 8 named frameworks with real unit maps: NGSS High School Physical Science, general High School Physics, AP Physics 1, AP Physics 2, AP Physics C: Mechanics, AP Physics C: E&M, IB Physics (all five DP themes), and NGSS Middle School Physical Science.
• PhET Interactive Simulations (Partial): No official first-party framework map found. The site hosts a community-submitted “Alignment of PhET sims with NGSS” activity, which is not the same as an official, maintained standards correlation.

Mapping depth

• OpenLab Science (Yes): Every mapped unit lists the specific labs that satisfy it — not a blanket “correlates to NGSS” tag. A teacher can open a framework page and see exactly which investigations cover which unit.
• PhET Interactive Simulations (No): No per-unit official mapping was found to evaluate.

Simulation & lab capability

Library size

• OpenLab Science (Yes): 138 curated presets across 8 physics modules (mechanics, fluids, waves, thermo, circuits, electricity & magnetism, optics, modern physics) — over our 100-preset bar for a full mark. Smaller than PhET’s 174 or Gizmos’ 550+, and narrower in scope — physics only, not general K-12 science.
• PhET Interactive Simulations (Yes): 174 interactive simulations, per PhET's own simulation filter (counted 2026-09-12) — the largest single free library among the products compared here.

Interactivity depth

• OpenLab Science (Yes): Every module is a buildable 2D scene — students place, connect, and configure real objects, not just move a slider on a fixed layout.
• PhET Interactive Simulations (Partial): Simulations are interactive with adjustable parameters, but generally not freely buildable scenes the way a sandbox is; depth varies a great deal by individual simulation.

Narrated lessons & built-in instruction

• OpenLab Science (Yes): 42 narrated concept lessons cover every preset: a law explanation, a formula symbol breakdown, a worked example, and self-check quizzes, presented by an avatar teacher with voice narration and captions. Text and voice are translated into all 46 UI languages, and any lesson replays from the preset guide.
• PhET Interactive Simulations (Partial): Some simulations can voice their own on-screen descriptions — a self-voicing accessibility feature that varies by simulation — but there is no narrated concept-lesson layer; PhET's teaching resources are written activities, not narrated instruction.

Live formula + SI-unit transparency

• OpenLab Science (Yes): The headline product differentiator: module formula panels evaluate the real symbolic formula with the scene’s current values live, and every readout carries its SI unit.
• PhET Interactive Simulations (Not confirmed): Could not confirm a consistent, platform-wide live substituted-formula display from public sources; behavior varies by simulation, and the absence of a central claim is not proof of absence.

Data tables, graphing & analysis

• OpenLab Science (Yes): Live graphs, a recorded measurement history, and readouts with units, exportable to CSV. Breadth varies by module.
• PhET Interactive Simulations (Not confirmed): Could not confirm a consistent, platform-wide data-table/graphing tool from public sources; varies by simulation.

Browser-based, no install

• OpenLab Science (Yes): Runs as an ordinary browser web app; no install, no plugin.
• PhET Interactive Simulations (Yes): Runs in-browser, with optional offline and app access also available.

Investigation & assignment workflow

Printable worksheets + answer keys

• OpenLab Science (Yes): All 138 presets have a printable 5E-model lab sheet, with a signed, email-verified teacher unlock for the filled-in answer key.
• PhET Interactive Simulations (Partial): Community and PhET-provided activity worksheets exist, alongside per-simulation Teacher Tips (behind a free sign-in), video primers, and alignment documents — but not every activity has a worksheet, and answer-key availability is inconsistent across the library.

Investigation notebook / evidence capture

• OpenLab Science (Yes): A structured investigation notebook and evidence-pack system covers all 138 presets, free and open to any teacher — no account or sign-up required.
• PhET Interactive Simulations (No): No integrated investigation notebook was found; external and community-authored activity sheets exist separately.

Teacher assignment, progress & grading tools

• OpenLab Science (Yes): Teacher assignment and grading tools cover all 138 presets, free and open to any teacher — build and share an assignment link in minutes, no account required.
• PhET Interactive Simulations (No): No native, in-product assignment collection, progress tracking, or grading was found — PhET Studio explicitly disallows student logins, so no student work flows back to a teacher. Its presets and teacher-resource library are a different thing.

Save / share a configured scene

• OpenLab Science (Yes): Every preset and every free-built scene is shareable as a compressed link — open it and the exact scene (entities, settings, instruments) reloads. The 10 curated presets additionally keep human-readable parameter links (?mass=2&vx=3…).
• PhET Interactive Simulations (Partial): Free simulations do not offer this. PhET Studio — paid — lets an educator save a configured launch state and share it by URL; sharing with a colleague requires them to hold a license too.

Data export (CSV or similar)

• OpenLab Science (Yes): Recorded measurement runs export to CSV with units and provenance metadata.
• PhET Interactive Simulations (Not confirmed): Could not confirm CSV export on free simulations from public sources. A separately licensed product, PhET-iO, supports streaming output data and programmatic control for developers.

AI guidance

AI tutor / assistant

• OpenLab Science (Yes): A free built-in AI tutor is shipped and genuinely lab-aware: its requests include the current serialized scene, live measurements, and the relevant formula context, not just a chat window bolted on the side.
• PhET Interactive Simulations (Not confirmed): No AI tutor or assistant was found on public PhET pages.

Accessibility & reach

Account-free student experience

• OpenLab Science (Yes): Every capability — labs, narrated lessons, printable sheets, assignment links, evidence packs, grading — works with no account anywhere in the product. A student on a shared classroom device never signs up or signs in.
• PhET Interactive Simulations (Yes): Simulations run with no account required — student accounts are not allowed at all. PhET's optional educator accounts (about 720,000 registered over five years) exist to share activities and teacher material; none of that is needed to run any simulation.

Accessibility

• OpenLab Science (Partial): Real accessible controls exist — ARIA roles/labels, live regions, keyboard and click fallbacks — but there is no public WCAG conformance statement or VPAT yet, unlike PhET or Pivot.
• PhET Interactive Simulations (Yes): The strongest accessibility program among the products compared here: pan/zoom (91 simulations), alternative input (64), interactive highlights (57), and self-voicing interactive description (13), backed by disability co-design and a published accessibility statement. Coverage varies by individual simulation.

Languages supported

• OpenLab Science (Yes): 46 UI locales (English, Arabic, Bengali, Bulgarian, Simplified & Traditional Chinese, Catalan, Czech, Danish, Dutch, Filipino, Finnish, Spanish, Swedish, French, German, Greek, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Norwegian, Persian, Polish, Brazilian Portuguese, Romanian, Russian, Slovak, Croatian, Slovenian, Lithuanian, Latvian, Estonian, Irish, Maltese, Malay, Marathi, Telugu, Tamil, Thai, Turkish, Ukrainian, Urdu, Vietnamese) — printable lab sheets are translated too.
• PhET Interactive Simulations (Yes): The most-translated simulations reach about 90 languages each (per PhET's own per-simulation translation lists, checked 2026-09-12) — more languages than any other product compared here, including OpenLab.

Translated teaching materials

• OpenLab Science (Yes): In all 46 languages: the interface, the printable lab sheets for all 138 presets, and the narrated lesson audio — text and voice, not just menus, but the materials a student actually reads and hears.
• PhET Interactive Simulations (Partial): The simulations themselves are translated (the deepest per-simulation coverage reaches about 90 languages) — a genuinely translated product. The teacher-activity library is community-contributed and not systematically translated.

Pricing

Free tier

• OpenLab Science (Yes): Every lab, every preset, every printable sheet, and the built-in AI tutor are free, with no account and no paywall.
• PhET Interactive Simulations (Yes): The entire core simulation library is free, with no account required. PhET is funded by grants and donations — and is transitioning the collection from a CC BY to a non-commercial (CC BY-NC) license, with the exact scope and date unconfirmed.

Paid tier / entry price

• OpenLab Science (No): None. There is no paid tier: the whole product, including the teacher tools, is free for students, teachers, and whole schools.
• PhET Interactive Simulations (Partial): PhET Studio, launched in 2025, sells saved-and-shared launch-state presets: $50 per editor per year (introductory; the $100 list price is struck through on the page), curriculum deployments from $5,000 per year, and custom commercial pricing — purchasable in the United States only. Studio collects no student work. The core library stays free either way.

When to use which — honestly

PhET remains the stronger choice for the widest possible simulation library, for the deepest accessibility program available today, and for a classroom that needs a simulation in a language OpenLab does not yet support. OpenLab is the stronger choice when a teacher wants a printable worksheet with a real answer key tied to the exact simulation the class ran, when standards alignment needs to be a specific unit-to-lab map rather than a general correlation, when a live substituted formula next to the running scene is the point of the lesson — or when the students' work needs to come back collected and graded, which neither the free simulations nor Studio accept. Many teachers reasonably use both.

The honest summary: PhET is bigger and has been accessible-by-design for longer. OpenLab is narrower, but every lab ships with a worksheet, an answer key, a live formula panel, and a real per-unit standards map behind it.