K12Chemistry

Chemistry for middle and high school.

Clear explanations and practice for when a classroom idea still feels difficult. Start with the question you need to answer, then connect observations to particles, measurements, equations, and evidence.

For students

Find a topic by the part that is confusing, work through a real lesson, and check your reasoning with explained answers.

Start with student resources

For teachers

Assign lessons in sequence, use ready-to-ask questions, and listen for the reasoning behind common misconceptions.

Open teacher guidance

From measurement to solutions

Six linked lessons build from observable matter to atomic models, reactions, quantity, and aqueous chemistry.

  1. 01Matter and measurementClassify matter, measure density, and describe uncertainty.
  2. 02Atomic structureRelate protons, neutrons, electrons, isotopes, and ions.
  3. 03Bonding and moleculesUse formulas and models to discuss structure and properties.
  4. 04Chemical reactionsUse observations and balanced equations to track change.
  5. 05StoichiometryCalculate with moles, ratios, limiting reactants, and yield.
  6. 06Solutions, acids, and basesConnect dissolving, concentration, dilution, pH, and neutralization.

Useful ways to study

Need a quick reminder?

Use the Chemistry cheat sheet for constants, units, formulas, common ions, the full periodic table, and selected element data.

Need practice?

Open a lesson, write your own answer first, and reveal the explained solution only after checking units and reasoning.

Need the bigger map?

The curriculum sequence shows prerequisites and useful entry paths through the lessons.