Copyright © 2014 jsd

Next Generation Science Standards
John Denker

1  Overview and Recommendation

The NGSS standard was promulgated in mid-2013 and slightly revised in 2017. At least a dozen states and the District of Columbia have adopted them (reference 1). If you want to read the standards for yourself, see reference 2.

The standard went through several drafts and an elaborate public comment process.

*   Contents

2  Process Issues

2.1  Too Many Errors

In the released standard, there are numerous basic errors of fact. These are so numerous and so basic as to seriously call into question the process that produced them.

Some glaring errors are listed in section 5. This greatly underestimates the number of errors, partly because the list is incomplete, but also because many errors that are listed only once in section 5 occur in multiple places in the standard, sometimes worded similarly, sometimes differently. Fixing one or two instances will not fix the underlying problem. Asking unpaid reviewers to catch all the mistakes is unreasonable. Expecting public review to result in consistency is foolish. Something with this many errors and inconsistencies should never have been sent out as a first public draft, let alone a second public draft, much less a final standard. The errors should have been caught at the alpha stage, during internal review. The process needs to be changed so as to provide for a thorough professional review by people who actually understand the subject matter ... preferably people who have hands-on experience in the field. Experience teaching the material out of textbooks is not sufficient, because there are many errors in the textbooks.

2.2  Errors Not Fixed

All of the bugs listed in section 5 were found in the second public draft, and were duly reported. Evidently nobody bothered to fix them.

Of the bugs I know about in the second public draft, about half of them remain in the final version. In most of the other cases, the bug disappeared because the topic was simply dropped. In relatively few cases was an incorrect statement replaced with a correct one.

Specific examples of abandonment (as opposed to repair) include the removal of passages defining stability in terms of energy (section 4.1) and the removal of essentially all mention of friction (section 3.1).

This doesn’t seem like a very professional approach to problem-solving.

The obvious conjecture is that the authors were under too much time pressure at the end (despite the fact that the drafting process had gone on for years). They didn’t have time to properly solve the problem, so they swept it under the rug.

2.3  Not Enough Diversity of Input

As another process issue: The process needs to bring in multiple types of expertise. For example, the 12th-grade standard must be based on

The standard seems far too incestuous, far too insensitive to what’s going on outside the education industry.

2.4  Process versus Product – A Parable

Suppose General Atomics is building a plant. There are blueprints for the foundation, and other blueprints for the stuff that gets built on top of the foundation.

If at some point you find there is something wrong with the foundation, namely a couple dozen ways in which the foundational blueprint violates the laws of physics, you don’t keep building! In the real world, you call a halt, you revise the foundational blueprint, you rework (to the extent necessary) the parts that have already been built, you propagate the changes through entire stack of blueprints to maintain consistency, and you proceed from there.

In addition, there is a rule that says “Fix it in such a way that it stays fixed”. That includes carrying out some kind of inquiry to find out what went wrong during the foundational design stage, and making sure that kind of thing never happens again. The point is to get rid of the entire category of mistakes, not just the latest exemplar from that category.

That’s how it is supposed to work in the real world. That’s what seems “realistic” to me.

We can contrast the proper real-world process with a dysfunctional bureaucratic process. It is a time-dishonored practice to say “We have such-and-such process and it produces such-and-such results, therefore the results must be OK.” I say No! The results are not OK, and nothing anybody says about the process is going to make them OK.

This is what I call the triumph of “process” over common sense. It is the sort of thing that gives bureaucracy a bad name. It is irresponsible and unprofessional. It is not to be tolerated.

Somebody needs to act like a grown-up and take responsibility. That means taking responsibility for the results. If correct results require changing the foundations, so be it. If correct results require changing the process, so be it.

Note that this parable applies directly to NGSS. Several people have said that vast parts of the standard were predetermined from the outset, and can never be changed because they are based on a pre-existing foundational document, namely the NRC Framework (reference 3).

2.5  Bureaucratic Focus

The motto on the NGSS site is “By States, For States”.

That reveals quite a lot about the NGSS process. Note that it does not say “for students” or “for teachers” or “for scientists”. There is every reason to take the motto at face value: NGSS is of the bureaucrats, by the bureaucrats, and for the bureaucrats.

Some folks might argue that you can’t put the scientists and teachers in charge; they would just mismanage the thing. You need to put managers in charge of the scientists and teachers. However ... that argument would carry more weight if the NGSS process hadn’t been so badly mismanaged.

2.6  Why Bother?

One must also ask whether a standard of this kind is worth the trouble. The NGSS site has some discussion of this point, but fails to make the case. It says «It has been 15 years since science standards were revised» but fails to demonstrate that standards of this kind (whether up-to-date or not) have ever served a worthwhile purpose.

A standards document is very far down the list of things that an ordinary teacher needs or wants for day-to-day classroom use. A decent textbook would be far more useful. We should focus efforts on things that support and empower teachers and students, rather than tormenting and constraining teachers and students.

3  Imbalance, Inconsistency, and Omissions

Omissions are not the main problem with the standard. However, it is worth briefly mentioning some of the omissions, to set the stage for a broader discussion of imbalance and inconsistency.

3.1  Technical, Topic-Specific Omissions

Surprising topic-specific omissions include:

One wonders whether these omissions are intentional.

Such omissions have some limited significance, insofar as standards documents are highly open to abuse. Wise guys have been known to argue that because gas laws are not mentioned in the standard, they should not be covered as part of the K-12 curriculum. (This can be seen as an application of the legal maxim expressio unius est exclusio alterius, which is not reliable, but people use it anyway.)

On the other hand, we should not get too worked up over omission of this-or-that domain-specific topic. Students will never learn in school more than a tiny percentage of what they need to know. Far more serious omissions are discussed in section 3.2.

3.2  Imbalance as to General Learning and Thinking Skills

The most important things students need to learn are how to learn and how to think.

That brings our attention to the most serious, glaring imbalances the standards document, namely the emphasis on breadth at the expense of depth, and the emphasis on domain-specific topics as opposed to learning skills and thinking skills. You might have thought that thinking and learning would be the pre-eminent, predominant “Crosscutting Concepts” but that is not the case. Note the following contrast:

Little or No Emphasis

  • The phrase “imagination and creativity” occurs only once, near the very end (page 101). There are no other references to either imagination or creativity.

  In Contrast: Heavy Emphasis

  • The words “stable” and “stability” and related terms occur more than 50 times (at all levels from 1st grade through high school). See section 4.1 and item 1 for more on this.

Intermediate Level of Emphasis

  • The word “check” (as in “check your work”) does not occur in the document. Checking the work is the cornerstone of the edifice we call critical thinking. Similarly, the word “skepticism” occurs only twice. The word “verify” occurs seven times ... always at the high-school level, not at any lower level.

    One could argue that the word “assess” is used as a near-synonym for “check”. This word occurs in 20 places, only one of which is prior to the middle-school level. This is by no means sufficient to get across the larger point about reasoning. It does not convey the importance, let alone explain how to do it, much less how to teach it.

The imbalances discussed in this section are in addition to the topic-specific omissions listed in section 3.1. Furthermore, the errors listed in section 5 are far more significant than any omissions, because requiring students to learn things that cannot possibly be true is the opposite and the enemy of critical thinking.

4  Hard-to-Understand Standards

4.1  Emphasis on Stability

The standard places tremendous emphasis on “stability”. However, despite diligent efforts, I cannot figure out what it means by this.

Stability and related terms are mentioned more than 50 times (even if we don’t count the Table of Contents) ... and each time, it is handled incorrectly.

In any case, the fundamental issue here is that I really don’t know what they mean. It is bizarre to place such heavy emphasis on a word and leave it undefined and unexplained.

The second public draft tried to define it, but the final version does not even try. The word still remains, and still receives heavy emphasis; only the definitions and explanations have been removed. To my way of thinking, this is not a very professional approach to problem-solving. See also section 2.2.

4.2  «Evaluate Questions»?

Consider the following hard-to-understand statement from the high-school section (page 83):

Students who demonstrate understanding can: ....

Evaluate questions about the advantages of using digital transmission and storage of information.

[Clarification Statement: Examples of advantages could include that digital information is stable because it can be stored reliably in computer memory, transferred easily, and copied and shared rapidly. Disadvantages could include issues of easy deletion, security, and theft.]

Believe it or not, this PS is a vast improvement over the corresponding item in the second draft standard.

The main issue here is that I cannot figure out what it means to “evaluate questions”.

Furthermore: why not cross out the words “the advantages of” from the PS? The words add nothing of value, and indeed tend to prejudge the issue.

5  Some Errors and Misconceptions

5.1  A List of Specific Errors and Misconceptions

Note this is nowhere near being an exhaustive list.

Page 81: In a few places, the standard tries to engage issues that are properly called stability. Even then, the word is left undefined and unexplained. For example:
provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics).

That is unequivocally wrong. That is not what the second law of thermodynamics says. The second law commonly requires a less uniform distribution of energy.

Uncontrolled systems always evolve toward more stable states – that is, toward more uniform energy distribution (e.g., water flows downhill, objects hotter than their surrounding environment cool down).

The stable equilibrium state does not correspond to uniform energy distribution. The obvious counterexample is a column of gas in a gravitational field.

In the real world, stability (in this sense) is fundamentally controlled by entropy. Alas entropy is not mentioned at all. If you want to argue that entropy is beyond the scope of the K-12 curriculum, that’s fine ... but then any factually-correct discussion of stability is also beyond the scope. The standard tries to explain stability in terms of energy, which is fundamentally incorrect. If teaching the correct idea is difficult, teaching an incorrect idea is not an acceptable substitute.

Page 50:
The term “heat” as used in everyday language refers both to thermal energy (the motion of atoms or molecules within a substance) and the transfer of that thermal energy from one object to another. In science, heat is used only for this second meaning; it refers to the energy transferred due to the temperature difference between two objects.

Heat cannot be equivalent to “thermal motion”, because in an ordinary solid, half of the heat capacity is associated with potential energy, not kinetic energy.

Also, in science, “heat” is not limited to temperature-driven transfers. There is a faction that wishes it were defined this way, but a standards document should not be used to drive a factional and pedantic agenda. The fact is, in science and even within this standards document there are multiple notions of heat, each of which has its advantages and disadvantages. The following examples are inconsistent with the temperature-driven transfer definition. As always «⋯» indicates a direct quote from this standards document.

Page 98:
The radioactive decay of unstable isotopes continually generates new energy within Earth’s crust and mantle, providing the primary source of the heat that drives mantle convection. Plate tectonics can be viewed as the surface expression of mantle convection.

There are multiple inequivalent definitions of the word “energy”, including the scientific definition (“kinetic energy”) and the service definition (“Enron Energy Services”). It is a tremendous disservice to students to use a non-scientific definition in a scientific context. The phrase “generates new energy” violates a bedrock principle of physics, namely local conservation of energy.

Page 98:
The total amount of energy and matter in closed systems is conserved.

That is a misstatement of the law of conservation of energy. In fact, energy is always conserved, period. It is constant in closed systems. Constancy is not the same as conservation. See reference 4.

Page 75 and page 79:
Students also develop understanding that the total momentum of a system of objects is conserved when there is no net force on the system.

Alas that is not the understanding that we want students to develop. Momentum is always conserved, period. It is constant when there is no net force. Constancy is not the same as conservation. See reference 4.

A correct statement of the conservation law can be found on page 79. It is always a bad sign when a standard is not consistent with itself.

Page 5:
A bigger push or pull makes things speed up or slow down more quickly.

Not true for sideways forces. That includes forces of constraint. That also includes magnetism.

The statement might have been OK if restricted to one-dimensional straight-line motion ... but no such restriction appears anywhere near here. Indeed, a few sentences earlier there was talk of a particle that follows a particular path, and a particle that turns.

Also: Using «push or pull» as a euphemism for “force” is silly.

Page 31:
The faster a given object is moving, the more energy it possesses.

Not true for objects in orbit. The fast orbiting object has more KE, but less overall «energy». This is obvious from the virial theorem, or from direct application of the kinematic laws.

Even if the intent was to say “the faster a given object is moving, other things being equal, ...” such a statement would be unacceptable, because any valid conclusion would depend on which other things are being held equal.

Page 48:
... stored (potential) energy ...

Evidently the intent was to imply that stored energy and potential energy are equivalent concepts. This is not true. Energy can perfectly well be «stored» in the form of kinetic energy, e.g. in a flywheel.

Page 16:
Scientists search for cause and effect relationships to explain natural events.

Sometimes they do, and sometimes they don’t ... especially not when it comes to basic physics. Questions of “why” often belong to metaphysics, not physics. Often there is an explanation rather than a cause. Galileo is often called the father of modern science, precisely because he permanently separated physics from metaphysics. Newton succinctly summarized this point when he said “hypotheses non fingo”. The basic laws must say what happens, they sometimes say how it happens, but they rarely say why it happens. See reference 5 and reference 6.

Page 79:
Empirical evidence is required to differentiate between cause and correlation and make claims about specific causes and effects.

We agree that it is super-important to distinguish causation from correlation ... but insisting on empirical (as opposed to theoretical) evidence is not the key distinction. In practice the distinction requires effort, skill, and sophistication, and is not well summarized by “empirical” or by any other single word. See reference 7.

Page 79:
Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter, as well as the contact forces between material objects.

That’s not true. In fact, any real explanation must include lots of interactions that take place above and below the atomic scale. At the large-scale end, gravitation is important for explaining everyday transformations of matter. On a smaller scale, nuclear interactions are necessary to explain the structure of matter. Perhaps the intent of the statement was to consider the atomic scale only, but if so it is very unclear and needs to be rewritten.

Perhaps more importantly, even at the atomic scale, the explanation in terms of «electric charges» is wildly incomplete. Electrostatics alone cannot explain the structure of a single atom, much less matter in general. Electrostatics alone would predict that all atomic electrons would collapse into the nucleus. All matter would collapse, becoming orders of magnitude denser than what we observe. The actual size of atoms and their resistance to «contact forces» owes as much to kinetic energy as it does to «repulsion between electric charges». In atoms, there is a balance between kinetic energy and electromagnetic interactions, in accordance with the laws of motion.

Support an argument that the gravitational force exerted by Earth on objects is directed down.

[Clarification Statement: “Down” is a local description of the direction that points toward the center of the spherical Earth.]

That’s weird. No such “argument” can be made; down is in the direction of the local gravitational force, by definition.

The clarification statement provides the opposite of clarification. It seeminly asserts that the earth is spherical and that down points toward the center of the earth ... neither of which is true. In fact, both are crude approximations, but that’s not what the statement says.

5.2  Discussion

  1. It must be emphasized that the list in section 5.1 is nowhere near exhaustive.
  2. All of the bugs listed in section 5.1 were present in the second public draft, and were duly reported. See section 2.2.

6  References

Liana Heitin,
“Next Generation Science Standards: Which States Adopted and When?”
Education Week, August 15, 2014
“DCI Arrangements of the Next Generation Science Standards”

The standard as a whole can be found as a 103-page PDF at:

Individual sections can be selected and displayed as HTML via:

National Research Council,
“Framework for K-12 Science Education”

A PDF version is available for download, free for all.

John Denker,
“Conservation as related to Continuity and Constancy”

John Denker,
“How to Define Hypothesis”
John Denker,
“Scientific Methods”
John Denker,
“Cause and Effect”
Copyright © 2014 jsd