Florida SC.8.P.9.1

Science8th GradeChanges in Matter

The Standard

Explore the Law of Conservation of Mass by demonstrating and concluding that mass is conserved when substances undergo physical and chemical changes.

Florida Next Generation Sunshine State Standards for Science

Teacher's field guide

What Students Need to Do: Students measure the total mass of materials before and after a physical change or chemical reaction. They keep the system closed and use their measurements to explain whether matter was gained or lost.
What Mastery Looks Like: Students collect accurate mass data and conclude that the total mass stays the same in a closed system. They can explain apparent mass loss by identifying gas or material that escaped.
Common Misconceptions: Students may think melting, dissolving, or reacting destroys matter. They may assume gases have no mass or that bubbling proves mass was lost. Small measurement differences may also be mistaken for real changes in mass.
How to Assess It: Give students data showing a sealed reaction has a mass of 82.6 grams before and 82.5 grams after. Ask whether mass was conserved and how measurement error could explain the difference.

Lesson moves

Seal baking soda and vinegar in a zip bag, measure the bag before and after mixing, then compare the results.
Ask students to explain why a burning candle gets lighter and name the matter that leaves the measured system.
Play a card sort matching physical and chemical changes with closed-system diagrams and balanced before-and-after mass measurements.
Compare the labeled mass of a sealed soda bottle before and after opening, then discuss where escaping carbon dioxide goes.

Free download

A ready-to-print activity worksheet aligned to SC.8.P.9.1, with an answer key for the teacher on its own page. No account needed.

PDF, US Letter, prints cleanly in black and white.

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