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Common Core LiteracyGrades 9–10Science & Technical

RST.9-10.4: Symbols and Key Terms in Science Texts

Also written as CCSS.ELA-LITERACY.RST.9-10.4 · Cluster: Craft and Structure.

Get the Frayer Model TemplateAll 29 Grades 9–10 Literacy Standards

The Official Wording

Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9-10 texts and topics.

Common Core State Standards, Grades 9-10, Reading: Science & Technical Subjects · Read it at the source · Checked October 14, 2026

What RST.9-10.4 Means in Plain English

Ninth and tenth graders work out what symbols and key terms mean in one specific science context. In a reading on instant cold packs, the plus sign in ΔH = +25.7 kJ/mol means the system takes in heat, not that anything gets hotter.

In grades 6 to 8 (RST.6-8.4), students did the same with texts and topics at that level. Ninth and tenth grade bring harder notation, like chemical equations and their state symbols. In grades 11 and 12 (RST.11-12.4), the texts and topics grow more advanced again.

RST.9-10.4 I Can Statements

  • I can explain what a symbol means in a specific science text.
  • I can use a text’s own definition of a key term.
  • I can tell a term’s science meaning from its everyday meaning.

RST.9-10.4 Worked Example

The passage decodes the equation behind an instant cold pack, and the weak answer reads its plus sign the everyday way.

Read the Story
Squeeze an instant cold pack and you break an inner pouch of water, which dissolves the solid ammonium nitrate packed around it. Within a minute the pack feels icy.Chemists write the change as NH₄NO₃(s) → NH₄⁺(aq) + NO₃⁻(aq), ΔH = +25.7 kJ/mol. The (s) marks a solid, and (aq), short for aqueous, marks ions dissolved in water.ΔH stands for the enthalpy change, the heat a system takes in or gives off. In this text, system means the chemicals doing the dissolving, and surroundings means everything else, from the plastic to your hand.A positive ΔH means the system gains energy, so the process is endothermic: heat flows from the surroundings into the system, and the surroundings cool. A hand warmer, with a negative ΔH, does the reverse.The unit kJ/mol gives the size of the change: about 25.7 kilojoules taken in for every mole, or 80 grams, of ammonium nitrate that dissolves.
A short passage written for this page.
Question: What do ΔH, its plus sign and (aq) mean in this text, and how does a positive ΔH explain why the pack feels cold?
Not Yet“Δ is a triangle that means heat, and the plus sign means heat is added, so the pack gets hotter. (aq) means water. The pack feels cold because ammonium nitrate is a cold chemical.”It reads the plus sign the everyday way, as “hotter,” which is backward here: in this text a positive ΔH means the system takes in heat, so the surroundings cool. It also shrinks (aq) to “water” and invents a “cold chemical” the text never mentions.
Meets the Standard“ΔH is the enthalpy change, ‘the heat a system takes in or gives off.’ The plus sign means the system gains energy, so dissolving ammonium nitrate is endothermic and heat flows ‘from the surroundings into the system.’ In this text the system is only the chemicals doing the dissolving, and my hand is part of the surroundings, so my hand loses heat and the pack feels cold. The (aq) after each ion means it is dissolved in water, and kJ/mol means about 25.7 kilojoules are taken in for every 80 grams that dissolve.”It defines each symbol the way this text uses it, keeps system and surroundings straight, and uses those meanings to explain the cold instead of treating plus as hotter.
Question Stems to Use
What does this symbol stand for in this text, not in everyday life?Does the text define the term? Where?What does the sign in front of the number tell you?Is your hand part of the system or the surroundings here?Rewrite the equation as one plain sentence.

Common Mistakes with RST.9-10.4

Reading a symbol the everyday way

“The plus sign means it gets hotter.”

Try this: Have students find where the text defines each symbol and copy that definition before they write a single sentence of explanation.

Losing track of the system

Counting the hand as part of the system that gains heat

Try this: Ask students to sketch a box around the system the text defines and draw an arrow showing which way the heat moves.

Skipping the small symbols

Reading NH₄⁺(aq) as just “ammonium” and ignoring the (aq)

Try this: Have students rewrite the whole equation as a sentence that accounts for every mark, including the state symbols, charges and units.

Where RST.9-10.4 Fits

Comes BeforeRST.6-8.4Work out the meaning of symbols and key terms in science texts at the grades 6 to 8 level.
AlongsideL.9-10.6Acquire and use general academic and domain-specific words and phrases accurately.RI.9-10.4Determine the technical and connotative meanings of words as a nonfiction text uses them.
Comes NextRST.11-12.4Work out symbols, key terms and domain-specific phrases in grades 11 and 12 science texts.

Practice RST.9-10.4

Vocabulary Worksheet GeneratorFree ToolEnter the key terms from a chemistry reading, such as enthalpy, aqueous and endothermic, and get a worksheet that asks for each term’s meaning in context.Chemistry termsGrades 9-10Meaning in context
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Quick Check

  1. What does (aq) mean in the equation?
  2. What does the plus sign in ΔH = +25.7 kJ/mol tell you?
  3. In this text, is your hand part of the system or the surroundings?

RST.9-10.4: Other Names

RST.9-10.4CCSS.ELA-LITERACY.RST.9-10.4

Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved. Official wording from the Common Core State Standards PDFs at corestandards.org, last checked October 14, 2026. The explanation, I can statements, example, mistakes and practice on this page are EMStudio’s own, written beside the official wording. They are not part of the standard.