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Developing a subject-topic index

School science subjects and topicsTo help our website visitors easily find and compare different curricula and resources, it is important that we classify every item that we review or describe by subject and topic. We need to develop a comprehensive list of subjects and topics and then use it consistently for classification of our textbook and resource reviews.

I must confess that every time I’ve sat down to sketch out a subject-topic list, I have quickly become completely overwhelmed and flummoxed. Am I over-thinking the problem, attempting to do the impossible, or simply failing to see the obvious pattern? Is there a volunteer who will take the lead in developing a useful school subject and topic list?

What am I talking about?

For our purposes, “subject” refers to the main disciplines of science, such as physics or biology. “Topic” refers to the subdivisions within subjects, such as inertia or momentum in physics, and cell structure or organ systems in biology. Both levels of classification are necessary because some books or individual resources will be about only one or several topics within an overall subject area. (“Keywords” constitute a third level, but they don’t need to be organized in any particular way, so it is not the concern of this discussion except where we need to decide when a term qualifies as a topic vs. a keyword.)

Harder than it looks

Classification of standard middle and high school textbooks by subject is fairly easy (biology, chemistry, physics). Those are full-year subjects that more or less cover the same range of topics in all curricula. But that’s about as far as “easy” takes us. In fact, even with these standard subjects, there are choices to be made. For example, do we call it biology or life science? Isn’t the middle school subject called “physical science” a combination of physics and chemistry? At the subject level (usually in grade 7 or 8), earth and space are often treated together as topics under “earth science”; do we follow this convention or consider earth science and astronomy to be two different subjects?

Typical elementary school curricula break down primarily by topic rather than subject. A textbook for a given year might contain units on the human body (biology or health), electricity and magnetism (physics), the solar system (astronomy), and plants (biology again). Depending on the curriculum, these units are separate books, so one might classify a given book (or unit of a textbook) by its main subject and topic (e.g., biology – human body). Either way, some basic list of topics is necessary within each general subject area.

Some initial thoughts

I think the subject-topic list should be just large enough to meaningfully classify most of the materials we might discuss, yet small enough to be useful, simple and intuitive. The question is, “What amount of detail is sufficient and optimal and what particular subject-topic titles are simple and direct enough to enable homeschool teachers (parents) to identify relevant items?”

I’ve perused the table of contents of several textbooks, but they use a variety of titles for main sections (topics). I’ve even looked at places like the PBS Nova TEACHERS website (, where they list the following subject areas for the teacher resources they have:

  • Anthropology
  • Archeology
  • Earth Science
  • Engineering
  • Environmental Science
  • Forensic Science
  • Geography
  • Health Science
  • History
  • Life Science
  • Math
  • Paleontology
  • Physical Science
  • Science & Society
  • Space Science
  • Technology

I’m not suggesting that this list is exactly what we need. It’s obviously customized to the range of topics represented in Nova programs. However, this Nova Teachers site is “standards-based” so topics are related to areas that are considered key subject and topics in education content. For example, environmental science is usually a major topic within middle school earth science and again in high school biology. Should we classify it as a subject or just a topic? Likewise, health science is split out from life science (biology), and that is probably appropriate at the subject level.

Science content standards as a guide

I have found it helpful to consider the National Science Education Standards (NSES) ( You can download the entire PDF document for free. The portion on “content standards” (pages 103-111) identifies several content “topics” in each of the following eight categories:

  • Unifying Concepts and Processes
  • Science as Inquiry
  • Physical Science (includes Chemistry)
  • Life Science
  • Earth and Space Science
  • Science and Technology
  • Science in Personal and Social Perspectives
  • History and Nature of Science

Obviously these are not directly school subjects, but a consideration of the main content standards for the three grade levels (K-5, 6-8 and 9-12) in each of these content categories is instructive with regard to the task of developing a subject-topic list. (You’ll have to view the document to see the list of individual standards in each of these categories.)

And what about the Christian perspective?

In addition to categorizing regular (merely secular) school subjects and topics, our site must provide an expanded list of topics and subjects relating to science and Christian belief. We need more detail in this area because our site will have much more content in this one area. Of course, discussion of Christian perspectives cuts across all subject areas (and all of content categories of the NSES). However, some topics are unique to the Christian audience.

If I were to add another content category and its standards to the NSES, it would be:

  • Science and Christian belief
    • Science and the Bible
    • Science and belief in God
    • Science and Christian theology
    • Science and Christian practice

Those seem like logically distinct areas within this additional category.

Putting it all together

Okay, so I’ve described some of the issues involved in developing a subject-topic list (or index). And I’ve suggested that it’s instructive to think about subjects and topics in relation to the NSES content categories (plus a new category specific to the Christian perspective). This provides a framework and a beginning, but I need help bringing it together into a final, practical subject-topic index. Ideas and suggestions, anyone?

Do I have a volunteer who’ll take the lead on this one?

— Doug

16 comments to Developing a subject-topic index

  • Patrick


    Would the Propædia Outline be a useful starting point?

    I recently found an website pointing to the state standards.

    I still working on envisioning what we are discussing. Is the thought a hierarchical outline of knowledge or system of tags, or a formless wiki?


  • Douglas Hayworth

    Thanks, Patrick. Both of those are really helpful and insightful links that are relevant to this topic. To answer your question, I’m just trying to come up with a basic list of school subjects (and main topics within each subject) so that our primary classification of each textbook or resource we review will be consistent. These would define the browse-by-subject navigation. A more loose and free list of tags and keywords would be more for search rather than browsing navigation. Does that help?

  • Patrick


    I thought of another taxonomy of science: the Wikipedia science portal:

  • Patrick

    Would this be correct then?
    Each textbook/resource would had a single ‘Primary Classification.’
    In addition each textbook/resource would have a set of topics that are covered.
    Further, reviewers are welcome to add tags for searching.

    I assume this will be done in WordPress.
    Each review will be a post.
    Categories and subcategories will be used for subjects and topics.
    Tags will be used for ‘tags.’

  • I did a cursory Google search for “School Science Topics.” I did find a list here:

    However, it seems to me that no such list will be completely satisfactory, since different jurisdictions, and different textbooks, will divide scientific knowledge in different ways. I doubt that anyone else has come up with a perfect list, either. That being the case, why not say that it’s an impossible job, and do the best you can, with that warning.

    The last group is fine, but perhaps should include a topic on the history of the interaction between Christianity and science, although it would be possible to cover that under the four topics given.

    Thanks for your work.

  • Douglas Hayworth

    Yes, we’re working in WordPress, but only the blog will be posts. Reviews and other content will be traditional pages, which don’t use the same category and tag functions. We will do the equivalent of tags (keywords) for pages, and those can be anything. However, the structured subject and topic index will be for the primary classification (implemented via custom fields). That being said, a single resource can be classified in more than one subject and topic, and one topic can appear in more than one subject — as long as we don’t go crazy with the replication.

  • I think better by example. Is this how you are thinking?

    Prentice Hall Science Explorer: Sound and Light. is a 7th grade textbook. I linked the Table of Contents. The primary Subject would be “Physical Science.”
    The Topics would be:
    Physics — Waves & Wave motion
    Physics — Sound waves
    Physics — Electricity and Magnetism
    Physics — Light
    Technology — Aeronautics

  • Douglas Hayworth

    Sorry for the two-day lag in checking comments. Yes, Patrick, that’s exactly the sort of thing I’m getting at. I’d like to generate one master list so that every time there’s a new book or curriculum about the same subject and topic that we want to review, we always use the same terms to classify it.

  • Kimberly Dawes

    1. If the audience is homeschoolers, one has to think like a homeschooler. They seem to split into either the textbook approach and the eclectic approach. The textbook people pretty much confine themselves to choosing a textbook by age/grade, but the eclectic homeschoolers will search under sub-subjects and sub-sub-subjects, then by age/grade. The searches need to be independent of the prior category. For instance, I might search the terms “Birds”, “Insects” (or sub-sub-subject of Butterfly), “Microbiology” or ” Nutrition” rather than the subject “Biology.”
    Under Earth Science- “Weather”, “Rocks and Minerals”….
    2. Within the homeschool community (and public school), Nature Study is “hot.” For many, Nature Study IS their entry into science.
    Nature Study
    Nature Study- Plants
    Nature Study- Plants- Gardening
    Nature Study- Plants- Native plants
    Nature Study- Wildlife
    Nature Study- Journals and Notebooks
    Nature Study- Field Guides
    Nature Study- Citizen-Scientist Opportunities (give links) (e.g., Monarch Watch, Master Naturalist certification, Master Gardener Certification, Junior Master Gardener Programs, Project Feeder Watch, and others)

    3. Additional search terms
    Biography (I would link Biography to other topics. For instance, John Glenn: A Memoir would be Biography-Space Science…. Other Biographies will not so easily be classified. A book on Galileo goes where????
    Resources and Reference books
    Robotics (Quick, is that engineering, technology, or science?)
    4. Very few American homeschoolers will search under the terms in the NSES standards, although the conceptual approach such as used in the Singapore-approved texts really do lead to a good understanding of science.
    5. Forget the phrase “STEM”. (Science, Technology, Engineering, Math): Popular among some educators, reviled in a NYT op-ed, pretty much unknown among non-scientist homeschoolers.

  • Kimberly Dawes

    Lab- Kits
    Lab- Supplies
    Lab- Books

  • Kimberly Dawes

    The Wiki Science/Categories and Main Topics Portal mentioned by Patrick 1/10 is interesting, however the terms are “too” scientific. The terms Rocks, Minerals, Robotics, Insects, and other basic words are not there per a “Find” search. His 1/12 reply and link seems to use more K-12 terminology.

  • Douglas Hayworth

    Hi Kimberly. I agree that the index should be intuitive for the average parent-teacher. It should not be too technical. At the same time, I would be hesitant to elevate terms like “Nature Study” to the level of subject or topic. All of science is nature study (although the term seems to be applied mostly to life science). To me, Nature Study seems more of a style of presentation rather than a distinct subject; I would use it as a keyword rather than a main subject. Then again, maybe that’s not right either. I really don’t know….
    Although I don’t want the list to be too technical, I also want it to make sense scientifically. For example, that one school site has “Biology” at the same level as “Botany”. The arrangement may correspond to discrete elementary school subjects, but it isn’t technically correct (botany is a subdiscipline of biology). On the other hand, it feels OK to me to let human health stand as a separate subject from biology or life science in general.

  • Patrick

    RE: Nature Study

    I would agree that many homeschoolers look for Nature Study.

    It seems to me that there are a number of ‘subjects’ that are really studies of multiple subjects. For middle school, the subject is Earth & Space Science; in college you get Geology, Meteorology, Oceanography, and Astronomy. Nature Study strikes me as such a ‘subject.’

    I would recommend that, there be a category of interdisciplinary subjects. Perhaps something like this:

    Interdisciplinary Science
    * General Science (Includes aspects of many sciences)
    * Nature Study (Includes aspects of Earth and Life Science)

    Even ‘Physical Science’ and ‘Earth & Space Science’ could be considered interdisciplinary.

  • Patrick

    RE: Lab

    The category of ‘lab’ seems to be related to the NSES category of ‘Science as Inquiry.’

    At the same time, ‘Lab-Kit,’ ‘Lab-Supplies,’ ‘Lab-model’ seem to be a new types of materials. They could be ‘Resources’ but are much different that science readers. Would equipment reviews make the project too big?

  • Douglas Hayworth

    Lab-Supplies and Lab-Kits, etc. are not subjects or topics. They are “formats” or “types” of curriculum material. Any given lab kit or supply would still have to be classified by subject and topic, just as any particular textbook would. For example, a kit for identifying minerals would fall under Earth Science – Minerals and Rock. A model of the solar system would fall under Astronomy – Solar System.

    In general, I really don’t think there’s much value in putting effort into discussing lab supplies and kits on this website, except to provide a list of suppliers. For the most part, there are not philosophical, theological and worldview issues to discuss about basic lab supplies. Right now, I see it a very low priority. Don’t misunderstand me, though; I do think we should consider and comment on the laboratory lessons associated with particular curricula. In any case, that’s off-topic for this discussion, since neither lab supplies nor lab lessons are subjects or topics.

    “Interdisciplinary Science” is a good option for catching things like nature study, where the particular book or program classified is actually entirely holistic in that manner. However, as I described in the blog, typical (traditional) elementary school textbooks might have several units (e.g., human body, plants, solar system, oceans) but I wouldn’t call that interdisciplinary. We might want to call the subject “General Science” but we’d definitely need to attach each of the four “topics” to it. If those units are separate books, then they would be classified into respective subjects (not “General Science”). Just to be clear, I would not bother to flag every general science book with topics like “scientific method”, which nearly every book will address in at least one chapter; Scientific Method is certainly a legitimate topic, but a book would need to have significant special focus on it to merit classification into that category.

  • Patrick

    Yesterday, I noticed an ambiguity in my thought. I’ve been using the word ‘subject’ in two senses. Primarily, I’ve thought of ‘subject’ as a ‘school subject’ meaning the title of a class, book or unit. Secondarily, I thought of ‘subject’ as discipline of science within knowledge.