RS4K Book 2 — Chemistry (Ch 2-5): K-2 atoms-first chapters. Foundation 100%, Gap 0.0%, Map Error 0.0%, Practices 92.9%, no FSEs. Acids and bases differ at the atom-group level (OH for bases; H for acids). Acid-base reactions taught as atoms exchanging between molecules. Recommended Deep.
| Program | RS4K - Science Book 2 — Chemistry |
| Publisher | Gravitas Publications Inc. |
| Author | Rebecca Woodbury, Ph.D., M.Ed. |
| Grade Band | Grades 2-4 |
Verdict: ✓ Recommended — Deep. Foundation_calc 100.0%, deep tier. Practices 92.9% green (book-wide score). Zero map errors. Zero confirmed FSEs.
Strict atomic-foundation scoring. The Chemistry quarter of Book 2 (Chapters 2-5) uses the atoms-and-molecules framework established in Ch 5’s universal claim as the explanatory anchor. Adjusted Gap 0.0%, Map Error 0.0%.
Chapters 2-5 introduce acids and bases as different molecules with H and OH atom groups, then teach acid-base reactions as atoms exchanging between molecules to form new molecules (water and salt). Taste is framed as molecular signatures. Ch 5 contains the universal claim that anchors the rest of the book: ‘everything around us is made of atoms and atoms combine to make molecules.’
"An OH group is just an oxygen atom and a hydrogen atom together. Most common acids have an H group — an H group is just a hydrogen atom." (Ch 3, p. 18)
"When an acid and a base meet, the atoms in the acid exchange with the atoms in the base... Now two new molecules have been made. The new molecules for this reaction are water and table salt (sodium chloride)." (Ch 4, pp. 26-29)
"We have learned that everything around us is made of atoms and atoms combine to make molecules. The food we eat is made of molecules, but not all of the food we eat tastes the same. Why? Different molecules in different foods make foods taste different." (Ch 5, p. 33)
FSE_CONFIRMED: 0. No factual science errors found.
Map errors: 0. No OAO error (REI-substance, REI-agent, LAE, AEC all zero).
Practices: 92.9% green. Six of seven NGSS scientific practices PRESENT; argument-from-evidence is PARTIAL. Every chapter operationalizes the full arc (question → hypothesis → experiment → data → conclusion). RATATAZ Experiment series provides hands-on investigations. The practices score is computed book-wide and applies identically to all five subject entries.
Nothing structural. The Chemistry chapters score clean on every WWG metric.
The five RS4K Book 2 subject entries (Chemistry, Biology, Physics, Geology, Astronomy) all share Foundation 100%, Adjusted Gap 0.0%, Map Error 0.0%, Practices 92.9% — the curriculum’s architecture is uniform across subjects because Chemistry establishes the universal atomic claim that every other subject uses.
| Total Passages Scored | 21 |
| Raw Gap Error | 0.0% (19 mechanism passages — all anchored at atoms-and-molecules level) FALSE = atoms/molecules not present before students are asked to explain. The student is navigating without a starting point. |
| Adjusted Gap Error | 0.0% (0 UNSCAFFOLDED — atomic foundation established in Chemistry quarter, used throughout) UNSCAFFOLDED = no atomic grounding at all. LESSON_ATOMS = atoms mentioned elsewhere in lesson but not connected to this concept. |
| Substance-Model Errors (REI) | 0 Curriculum treats a process or outcome as a substance - "heat flows," "energy is stored," "electricity flows like water." Student builds a substance ontology. |
| Label-as-Explanation (LAE) | 0 Curriculum provides a name and treats it as an explanation - "this happens because of gravity." Student believes knowing the name IS understanding the concept. |
| Vague-Entity Errors (AEC) | 0 Curriculum uses vague entities ("tiny particles," "building blocks") without specifying atoms or molecules. Student invents their own model with macroscopic properties. |
| Factual Science Errors (FSE) | 0 Statements that are scientifically incorrect - not imprecise framing, but wrong. Any confirmed FSE = Not Recommended. |
| Practices | 92.9% - Deep Seven practices scored PRESENT, PARTIAL, or ABSENT and averaged: asking questions, developing and using models, planning and carrying out investigations, analyzing and interpreting data, using mathematics, constructing explanations and designing solutions, and argument from evidence. Higher is better, the opposite direction from gap and map errors. Reported but not part of the Foundation Score or the verdict. |
Acids and bases differ at the atom-group level (OH for bases; H for acids). Acid-base reactions taught as atoms exchanging between molecules. Universal atomic claim established in Ch 5 anchors the rest of Book 2.
Atomic foundation established in Chemistry (Ch 2-5) used throughout Book 2. Acids and bases differ at the atom-group level (OH for bases; H for acids). Acid-base reactions taught as atoms exchanging between molecules. Universal atomic claim established in Ch 5 anchors the rest of Book 2. Practices 92.9% green (book-wide).
Recommended (Deep) — Deep by design -
Evidence for every entry is published at three levels. Each level states what it contains and what it leaves out.
Scores, verdict, and the full pattern count for this unit are above: adjusted gap, REI / LAE / AEC counts, FSE status, and the seven-practice score. Passage-level detail for this unit is carried in the downloadable evidence file.
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