Conservation of mass is the focus of this Grade 7 Science worksheet on mass accounting in chemical reactions. Students apply the conservation of mass to closed-system reactions, relate reactant masses to product masses, and compare theoretical and measured yields using reaction completeness.

Build Reasoning Around Mass in Reactions

This resource moves beyond recalling the conservation of mass principle by asking students to use it in reaction-accounting situations. They examine how the masses of reactants and products are related in a closed system and use that relationship to reason about reaction outcomes.

Students also explore the difference between theoretical yield and measured yield, connecting the comparison to the completeness of a reaction. These ideas provide focused practice for the Matter and Chemical Change unit while strengthening students' ability to explain quantitative relationships in chemical reactions.

What Students Work Through

• Multiple-choice questions reinforce conservation of mass and reaction-accounting concepts.
• True-or-false questions check understanding of mass relationships in closed systems.
• Short-answer questions require students to explain how reactant and product masses relate.
• A reading passage places the conservation of mass concept into context.
• A matching activity reinforces connections among key reaction-accounting ideas.
• A cloze passage provides focused vocabulary and concept practice.
• An essay asks students to develop a written explanation of the science.
• A “Did You Know?” section provides an additional point of interest related to the lesson.

Included Teacher Support

The purchase includes a Student Notes & Lesson Summary supplement for student review and a separate Teacher Guide PDF. The guide contains Learning Objectives, Teaching Tips, Discussion Questions, and Common Mistakes to support instruction and address potential misconceptions.

Practical Classroom Use

Use this Grade 7 conservation of mass practice during a Matter and Chemical Change lesson, as guided or independent work, for concept reinforcement, or as a review activity. The varied response formats give students opportunities to recognize, explain, and apply the relationship between reactant and product masses without separating the practice from the core science concepts.

With its emphasis on closed-system reactions, mass accounting, theoretical yield, measured yield, and reaction completeness, this resource gives teachers a focused way to reinforce an important foundation of chemical change. The resource is identified with the Alberta framework.