Pure substances and mixtures are the focus of this Grade 7 Science resource for Ontario. Students classify materials by composition and uniformity, distinguishing elements, compounds, and mixtures while applying those ideas to familiar examples such as distilled water, salt water, air, alloys, solutions, and suspensions.

Classify Matter by Composition

The reading passage establishes the defining features of a pure substance: fixed composition and consistent properties throughout a sample. Students examine how an element contains one kind of atom, while a compound contains two or more elements chemically combined in a fixed ratio. They then contrast these materials with mixtures, where substances are physically combined and the composition can vary.

Real examples help students connect classification to observable material properties. Salt water can contain different proportions of water and dissolved salt, while air is a mixture of gases. Students also distinguish uniform mixtures such as certain solutions from non-uniform mixtures such as suspensions, and identify alloys as mixtures of metals.

Practice Scientific Classification

• Multiple-choice questions ask students to classify samples and apply definitions involving composition, uniformity, elements, compounds, mixtures, alloys, air, and suspensions.
• True-or-false questions reinforce key distinctions between pure substances and mixtures, including fixed composition and chemical combination.
• Short-answer prompts require students to explain why salt water is a mixture, identify variable properties, and compare compounds with mixtures.
• A matching activity reinforces definitions and relationships among the central classification terms.
• A cloze passage gives students contextual practice with pure substances, elements, compounds, mixtures, salt water, air, and suspensions.
• An extended response asks students to use material-classification concepts when choosing materials that require consistent properties.
• A “Did You Know?” section adds further context to the lesson topic.

Ready for Classroom Use

Use this Grade 7 science worksheet for introducing pure substances and mixtures, guided practice, independent work, review, or assessment preparation. The examples give students concrete situations for deciding how materials should be classified and explaining why composition matters when identifying or selecting substances.

Teacher and Student Support

• ✅ Student worksheet covering pure substances, elements, compounds, and mixtures
• ✅ Separate PDF answer key for checking student responses
• ✅ Student Notes & Lesson Summary supplement for review and reinforcement
• ✅ Separate Teacher Guide with learning objectives, teaching tips, discussion questions, and common mistakes

Designed for Ontario Grade 7 Science, this resource gives students structured practice with the vocabulary and reasoning needed to classify materials accurately and connect chemical composition with consistent or variable properties.