Elements and Compounds

Overview

In this first lesson of the three-part unit “Elements, Compounds, and Change,” students build on their understanding that matter is made of atoms. Using real objects, picture cards, and a visual sort, they distinguish elements from compounds and practice using chemical symbols and formulas. Students also connect familiar elements to Earth, living matter, oceans, and the atmosphere.

Learning intentions

Students will be able to:

• Define element, compound, chemical symbol, and chemical formula.
• Distinguish an element from a compound using particle composition.
• Identify hydrogen and oxygen by name, symbol, and common location.
• Classify examples as elements or compounds using visual and physical evidence.

Success criteria

• I can explain that an element contains one type of atom.
• I can explain that a compound contains two or more elements chemically joined.
• I can identify hydrogen as H and oxygen as O.
• I can correctly sort examples into elements and compounds and explain one choice.

Curriculum links

• Matter classification: investigating physical properties to distinguish pure substances, solutions, and heterogeneous mixtures.
• Elements: identifying elements by their properties and importance to modern life.
• Matter and atoms: recognizing that matter is made of atoms and can be classified according to its properties.
• STAAR Alternate 2 focus: identifying and classifying elements and compounds using visuals and familiar examples.

Lesson structure (30 minutes)

1. 0–4 min · Hook and connect. Teacher displays a photo of oxygen in the atmosphere, water in an ocean, and a copper wire using the hook and opening images and asks, “Are these all made of the same kind of matter?” Students silently predict, then share one idea with a partner.

2. 4–10 min · Direct teach vocabulary. Teacher uses the vocabulary and particle-model slides to explain that an element is a pure substance made of one type of atom, while a compound is a pure substance made when two or more different elements are chemically joined. Introduce chemical symbol and chemical formula, emphasizing hydrogen (H), oxygen (O), water (H₂O), and carbon dioxide (CO₂). Students repeat the terms, match each word to its meaning on the elements and compounds practice sheet, and sketch one simple particle model.

Clarify that a symbol represents an element, while a formula represents a substance and shows which elements are present. Explain that the small number in a formula tells how many atoms of that element are present.

3. 10–16 min · Real-object observation. Teacher shows or passes safe examples such as copper wire, aluminum foil, water in a clear cup, and a carbonated drink, using the real-object observation prompts to ask what students can observe and what they can infer. Students work in groups of three to record each item as a likely element or compound, giving one reason. Teacher reminds students that appearance alone cannot always prove a substance’s identity; the focus is using the model, name, symbol, or formula provided.

4. 16–24 min · Visual sort. Teacher gives each group a set of teacher-prepared picture and formula cards: hydrogen (H), oxygen (O), copper (Cu), iron (Fe), water (H₂O), carbon dioxide (CO₂), and sodium chloride (NaCl). Students use the visual-sort instructions and examples to place cards under “Element” or “Compound,” then complete the matching section on the elements and compounds practice sheet. Each student must explain at least one placement using the sentence frame, “I classified ___ as a ___ because ___.”

5. 24–27 min · Where are elements found? Teacher displays the Earth, living matter, oceans, and atmosphere map and discusses accessible examples: oxygen and nitrogen in the atmosphere, hydrogen and oxygen in ocean water, carbon in living matter, and minerals and metals in Earth’s rocks and soil. Students choose one example and complete the sentence, “The element ___ is important/found in ___ because ___.” Teacher accepts oral, written, drawn, or selected responses.

6. 27–30 min · Check and close. Teacher asks students to hold up one finger for element or two fingers for compound as the following examples appear on the final review and exit questions: O, H₂O, Cu, and CO₂. Students complete the final three questions on the elements and compounds practice sheet: define an element, classify H₂O, and write the symbol for oxygen. Teacher collects the sheets and addresses any misconception before the next lesson.

Resources

• the Elements and Compounds slide deck
• the elements and compounds practice sheet
• Teacher-prepared picture and formula cards
• Safe real objects: copper wire, aluminum foil, clear water, and a sealed carbonated drink
• Clear cup or container
• Board or chart paper and markers
• Pencils and colored pencils
• Optional periodic table display

Assessment

• During direct instruction, listen for accurate use of element, compound, symbol, and formula; ask students to explain the difference in their own words.
• During the visual sort, check whether students use the number and types of elements in a formula rather than relying only on an object’s appearance.
• Use the final worksheet questions and finger responses to identify students needing reteaching, especially students confusing a compound with a mixture or confusing an element’s name with its symbol.

Differentiation

• Provide picture-supported vocabulary, color-coded particle models, and the sentence frame “___ is an element/compound because ___.”
• For students needing additional support, limit the first sort to H, O, H₂O, and CO₂; read formulas aloud and allow oral, pointing, or drawing responses.
• Pair students strategically and assign roles such as card reader, sorter, and explainer. Preteach the words atom, joined, symbol, and formula to multilingual learners.
• Challenge ready students to explain why H₂O is a compound even though it contains hydrogen and oxygen, and to identify the elements shown in CO₂ and NaCl.