Mississippi Science PHS.1.3

ScienceGrades 9–12Physical Science

The Standard

Conduct an investigation to determine the identity of unknown substances by comparing properties to known substances.

2026 Mississippi College- and Career-Readiness Standards for Science · Nature of Matter

Teacher's field guide

What Students Need to Do: Students test safe, unlabeled samples and record how they behave in the same tests as known substances. They compare properties, such as solubility and reaction with vinegar, to identify each sample.
What Mastery Looks Like: A student uses the same amount and test steps for known and unknown powders. They use a results table to rule out other candidates and say when the evidence is not enough.
Common Misconceptions: Students may identify white powders by color alone or assume two powders that dissolve in water must be the same substance. They may mistake fizzing in vinegar for dissolving.
How to Assess It: Give students a table showing that salt and baking soda both dissolve in water, but only baking soda fizzes with vinegar. Ask which powder a coded sample is if it dissolves and fizzes, and what result rules out salt.

Lesson moves

Give pairs labeled and coded samples of salt, baking soda, and sand; test equal pinches with water and vinegar, then match results.
Ask: If two white powders both dissolve in water, are they the same substance? Defend your answer using a second test.
Hand out property cards for three known powders and coded test results; teams match each sample and name one ruled-out candidate.
Give a mock road-maintenance report with water test results; students identify an unlabeled bag of road salt or sand before spreading it.

Free download

A ready-to-print activity worksheet aligned to PHS.1.3, 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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