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Editorial Note
This article is based on direct review of the published scope-and-sequence documents for each curriculum, sample lessons from each (where publicly available), review of NGSS alignment documentation where claimed, and aggregated homeschool-family feedback from r/Homeschool, the Secular Homeschool Forum, and Cathy Duffy Reviews. We have not yet run a full academic year with any single curriculum; a multi-year comparative pass is in planning. Where we report direct observation vs aggregated feedback, we say so.
Why “Secular” Matters
The US homeschool curriculum market is heavily weighted toward Christian and explicitly faith-integrated publishers. Apologia, Masterbooks, Abeka, BJU Press, and Sonlight dominate shelf space at homeschool conventions and comprise the first five results for most “homeschool science curriculum” searches. For secular, atheist, agnostic, Jewish, Muslim, or Christian-but-preferring-science-neutral families, that mainstream selection doesn’t fit.
Secular homeschool science is a smaller segment with real options that often don’t get the same marketing reach. The five curricula below are all explicitly secular — they teach evolution, deep time, and the age of the universe according to mainstream scientific consensus, without editorial framing around young-earth creationism or faith-based alternative explanations.
The Short Answer
| Priority | Choose |
|---|---|
| Lowest daily prep, open-and-go | Mystery Science |
| NGSS-aligned, most academically rigorous | BFSU (Building Foundations of Scientific Understanding) |
| Hands-on kit-driven, experiment-heavy | REAL Science Odyssey |
| Lowest cost / free-tier | OpenSciEd + Mel Chemistry supplement |
| Topic-rotating interest-driven | Elemental Science Secular Physical/Biology |
The Curricula Compared
1. Mystery Science — $99/year (Mystery Elementary) or $249/year (full K–5 access)
| Type | Video-led + hands-on project curriculum |
| Daily prep | 5–10 minutes (preview the lesson) |
| Grade coverage | K–5 |
| NGSS alignment | Yes, explicitly |
| Format | Video-based “mysteries” (open questions kids investigate), + hands-on activity per lesson |
| Sample lesson length | 30–45 minutes |
| Secular positioning | Explicitly secular, evolution-affirming |
| Parent skill required | Low — the video does the teaching |
Why it wins on low-prep: Mystery Science was built by former teachers specifically for the open-and-go model. A parent who has 10 minutes to queue the lesson can deliver a full science class. The “mystery” framing (e.g., “Why do we have thumbs?”, “How can a skyscraper survive an earthquake?”) is pedagogically solid — it mirrors inquiry-based learning practices that the NGSS Framework explicitly endorses.
What buyers report: Highly engaging for K–3; some report 4th-5th graders find the video pacing slightly young. Hands-on activities use common household materials (paper plates, tape, string) 80% of the time; occasional need for a specific item.
Who it’s for: Families who need their science curriculum to happen reliably despite a parent who is not a science teacher and does not want to become one.
2. BFSU (Building Foundations of Scientific Understanding) — $32/volume (three volumes)
| Type | Concept-progression text-based curriculum |
| Daily prep | 30–60 minutes (parent reads ahead, plans demonstrations) |
| Grade coverage | Volumes I (K–2), II (3–5), III (6–8) |
| NGSS alignment | Aligned in principle but predates NGSS; author Bernard Nebel designed around developmental cognitive progression |
| Format | Text-based lesson book + parent-led demonstrations + discussion questions |
| Sample lesson length | 45–90 minutes |
| Secular positioning | Explicitly secular, built on evolutionary biology and standard cosmology |
| Parent skill required | High — parent delivers the instruction |
Why it wins on rigor: BFSU is the most academically substantive secular elementary science curriculum available. It’s structured around Bernard Nebel’s thesis that children develop scientific understanding through specific concept progressions — “Matter & Atoms” builds through stages that each presuppose the prior stage. A child who completes all three volumes of BFSU has a K–8 science foundation comparable to a strong school program.
What it costs beyond the books: BFSU’s demonstrations require hands-on materials the parent sources (magnifying glasses, thermometers, basic chemistry supplies). Plan an additional $150–$300 over a multi-year arc, though many items are reusable.
What buyers report: “This is work” is the recurring note. Parents who commit to BFSU’s prep-heavy model report excellent outcomes; parents who try to do it casually often drift back to a lighter curriculum. Cathy Duffy has written approvingly about BFSU; the Secular Homeschool Forum rates it the gold-standard secular science curriculum at the elementary level.
Who it’s for: Homeschool parents who want their child to have a genuinely rigorous science foundation and are willing to invest real prep time.
3. REAL Science Odyssey (RSO) — $38–$55/level (second edition) + lab kits
| Type | Text + experiment-based curriculum |
| Daily prep | 15–30 minutes |
| Grade coverage | Full K–12 progression |
| NGSS alignment | Partial — aligned on content, less explicitly on practices |
| Format | Textbook + lab manual + materials list (optional companion kit) |
| Sample lesson length | 45–60 minutes |
| Secular positioning | Explicitly secular |
| Parent skill required | Medium |
Why it’s on the list: RSO (by Pandia Press) is the most experiment-heavy secular curriculum at the elementary level. Lessons consistently center around a hands-on activity rather than text-first reading. For kinesthetic learners or kids who strongly prefer “doing science” over “reading about science,” RSO delivers more lab-style time than either Mystery Science (video-first) or BFSU (text-heavy).
What buyers report: Solid content, good pacing, occasional frustration with materials-list complexity (some experiments need specific items that require separate sourcing). The companion kit reduces this friction but adds cost.
Who it’s for: Hands-on learners. Families who would rather do 40 experiments than read 40 chapters.
4. OpenSciEd — Free
| Type | Free NGSS-aligned open curriculum |
| Daily prep | 30–60 minutes (parent adapts from classroom-oriented materials) |
| Grade coverage | Currently strongest at middle-school; elementary being expanded |
| NGSS alignment | Yes, built from the ground up on NGSS |
| Format | Teacher guides, student materials, phenomenon-based units |
| Sample lesson length | Variable (units designed for classroom pacing; adapt for homeschool) |
| Secular positioning | Explicit — developed by Columbia Teachers College and partner institutions |
| Parent skill required | Medium-high — adaptation from classroom to homeschool required |
Why it’s on the list: OpenSciEd is the free, rigorous, NGSS-aligned curriculum that the elementary-secular market has been missing. It’s fundamentally designed for classroom use, which means homeschool parents have to adapt materials, but the content quality is on par with any paid curriculum. For families whose budget is the primary constraint, OpenSciEd plus a modest supplement (a subscription box like Mel Chemistry for ages 10+, or a Thames & Kosmos Chemistry kit) delivers college-prep-quality elementary science for under $200 per year.
What buyers report: The classroom-to-homeschool adaptation is real work. Parents who pair OpenSciEd with a structured supplement (hands-on kit, lab materials) report strong outcomes; parents who try to use OpenSciEd as-is without adaptation sometimes drift.
Who it’s for: Cost-sensitive families with at least one parent who can invest the adaptation time. Also: educators transitioning from classroom to homeschool.
5. Elemental Science Secular — $35–$65/level
| Type | Topic-rotating curriculum (biology / earth & space / chemistry / physics year-by-year) |
| Daily prep | 15–30 minutes |
| Grade coverage | K–8 |
| NGSS alignment | Partial — content-aligned, practices less emphasized |
| Format | Text + experiment + notebooking |
| Sample lesson length | 30–60 minutes |
| Secular positioning | Elemental Science now offers explicit “secular” editions that remove the religious framing from their earlier products. Verify you’re buying the Secular edition specifically. |
| Parent skill required | Medium |
Why it’s on the list: Elemental Science’s topic-rotation model (one year of biology, one of chemistry, one of physics, one of earth & space) is pedagogically distinct from the concept-progression model of BFSU. For kids who thrive on depth-in-one-topic rather than breadth-across-topics, this format fits better. The secular edition (available since ~2020) is genuinely secular; the same brand’s older faith-integrated products remain available, so check the specific edition.
Who it’s for: Families who prefer year-long deep dives into single topics.
The Head-to-Head Comparison
| Mystery Science | BFSU | REAL Science Odyssey | OpenSciEd | Elemental Science Secular | |
|---|---|---|---|---|---|
| Cost (per year) | $99–$249 | ~$32 (one volume across 2–3 years) | $38–$55 + kit costs | Free | $35–$65 |
| Parent prep | Very low | High | Medium | Medium-high | Medium |
| Academic rigor | Medium | Highest | Medium-High | High | Medium-High |
| NGSS alignment | Explicit | Aligned | Partial | Native | Partial |
| Hands-on density | Medium | Medium | Highest | Variable | Medium |
| Best fit | Low-prep household | Rigor-first household | Kinesthetic learners | Budget-first, adapt-capable parent | Year-long topic immersion |
What to Supplement With
No single curriculum above is a complete K–5 experience on its own. Every homeschool family we’ve worked with pairs their “primary” curriculum with 1–2 supplements:
- A hands-on kit that extends the experiment-density: Thames & Kosmos Kids First Chemistry ($40), Snap Circuits Jr ($35), or GraviTrax ($60) are standard picks.
- A subscription for structured novelty: See our KiwiCo Alternatives piece for the decision tree. For ages 5–8, Kiwi Crate remains a reasonable supplement to any of the curricula above. For ages 10+, Mel Chemistry pairs particularly well with BFSU or OpenSciEd.
- A nature-study component: None of the curricula above emphasize outdoor science as a daily practice. Adding a weekly nature walk with a field guide (Peterson or Sibley) is a zero-cost enhancement that secular homeschool communities consistently recommend.
- Quality library access: Pairing any curriculum with a weekly trip to the public library to pull age-appropriate science books (DK series, National Geographic Kids, Scientists in the Field from HMH) dramatically extends what the curriculum alone delivers.
What the Research Says
The general literature on homeschool science outcomes is thin — homeschool families are a self-selected, heterogeneous group, which makes research difficult. Ray (2010) documented broadly comparable academic outcomes between homeschooled and conventionally-schooled students at the elementary level,1 but the sample was not disaggregated by curriculum choice. For our purposes, the relevant research is on the underlying pedagogical approaches:
- Inquiry-based learning (Mystery Science’s approach) has strong empirical support across grade levels.2
- Concept progression (BFSU’s approach) is grounded in Piagetian cognitive development research — a classical frame that has held up in its general contours despite refinements.
- Lab-intensive learning (RSO’s approach) is supported by the NRC 2012 Framework as one of the core practices of effective science education.3
None of the curricula have been independently studied for outcomes. The research supports the pedagogical approaches they each use, not the specific products. This is the same caveat we apply to every content recommendation on this site.
Our Recommendation
For most secular homeschool families starting out: Mystery Science for K–3, transitioning to BFSU Volume II for grades 3–5. This combination starts low-prep for young learners where the cognitive load should be on the parent learning to homeschool, then ramps into rigorous material as the child (and parent) is ready.
For budget-constrained families: OpenSciEd as the core, plus one Thames & Kosmos kit per year for hands-on reinforcement. Total first-year cost: ~$40.
For hands-on-driven families: REAL Science Odyssey with the companion lab kits. More expensive but consolidates the experiment-heavy experience most kinesthetic kids benefit from.
For deep-dive-style learners: Elemental Science Secular’s topic-rotation, one topic per year.
Sources
- OpenSciEd: openscied.org
- Mystery Science: mysteryscience.com
- BFSU: Available via Amazon and BFSU’s own book sales
- REAL Science Odyssey: pandiapress.com
- Elemental Science: elementalscience.com (confirm secular edition)
- Cathy Duffy Reviews: cathyduffyreviews.com
- Secular Homeschool Forum: secularhomeschool.com
This article will be updated as we run longer-horizon homeschool curriculum comparisons. A multi-year academic tracking of at least two of the curricula above is in planning.
Footnotes
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Ray, B. D. (2010). “Academic achievement and demographic traits of homeschool students: A nationwide study.” Academic Leadership, 8(1). ↩
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Furtak, E. M., Seidel, T., Iverson, H., & Briggs, D. C. (2012). “Experimental and quasi-experimental studies of inquiry-based science teaching: A meta-analysis.” Review of Educational Research, 82(3), 300–329. ↩
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National Research Council. (2012). A Framework for K-12 Science Education. National Academies Press. ↩