My child understands the concepts but keeps getting stoichiometry problems wrong. What is going on?

Almost always the conversion path, not the chemistry. The three-step grams to moles to moles to grams route has to be set up before any calculating, and students who start typing numbers into a calculator immediately lose track of which substance each figure belongs to. Sessions focus on writing the plan out first.

Does chemistry require more maths than biology?

Yes, noticeably. Moles, molarity, gas laws, and percent yield all involve multi-step calculation with units attached. Students who are shaky on rearranging equations or on scientific notation tend to struggle in chemistry even when they follow the ideas well.

How do you help with memorising polyatomic ions?

Through recall practice in conversation rather than a list to stare at. Evelyn Tutor asks for formulas and charges at intervals during other work, so nitrate, sulfate, and carbonate come up repeatedly while solving naming and stoichiometry problems.

Can this help without access to a lab?

It covers the calculation, notation, and reasoning parts of the course, and can talk through the purpose and expected results of standard experiments such as titrations or a hydrate mass-loss lab. It does not replace hands-on lab time or supervise practical work.

Chemistry

High School (9-10) · Science

High school chemistry in years 9-10 is where students move from describing matter to accounting for it: counting particles with the mole, tracking atoms through balanced equations, and predicting what a reaction will produce. Most difficulty comes not from the chemistry ideas themselves but from the arithmetic and unit-tracking that carry them. Evelyn Tutor works through problems out loud with the learner, asking them to state what each number represents before calculating, so mole ratios and formula subscripts stop being interchangeable symbols.

Start a session on Chemistry

What this covers

Reading the periodic table for electron configuration, valence electrons, and periodic trends in atomic radius, ionisation energy, and electronegativity
Writing formulas and names for ionic and covalent compounds, including polyatomic ions and transition metals with Roman numerals
Balancing chemical equations and classifying reactions as synthesis, decomposition, single replacement, double replacement, or combustion
Mole conversions: grams to moles to particles, molar mass from a formula, and percent composition
Stoichiometry from a balanced equation, including limiting reactant and percent yield problems
Solutions and molarity, dilution calculations, and the pH scale for acids and bases
Gas laws (Boyle, Charles, combined, and the ideal gas law) with correct use of Kelvin

Where learners get stuck

Changing a subscript instead of adding a coefficient when balancing an equation: Both make the numbers work out, so students treat them as equivalent. They have not yet internalised that a subscript defines which substance it is — changing H2O to H2O2 produces a different chemical, while a coefficient only says how many units react.
Treating the mole as a mass unit rather than a count: Molar mass is given in grams and every mole problem involves a balance, so 'mole' gets mentally filed as a heavier gram. Students then add moles of different substances together or use grams directly in a mole ratio.
Assuming the reactant with the smaller mass is the limiting reactant: It matches everyday intuition about running out of the smallest ingredient. It ignores that the coefficients set the required ratio and that a light substance can supply far more particles per gram than a heavy one.
Using Celsius in gas law calculations: Temperature is normally reported in Celsius in class and lab, and the formula does not visibly object. Ratios only work from absolute zero, so a 20°C to 40°C change is not a doubling.

What a session looks like

A session usually starts with the learner reading a problem aloud and saying what is being asked before touching any numbers. Evelyn Tutor asks for the balanced equation first, then the units of each given quantity, then the plan — often having the student describe the conversion path in words before calculating. Wrong answers are traced back to the step where the unit stopped making sense rather than simply corrected. Sessions can also focus on drilling ion names and formulas, or on talking through why a periodic trend behaves as it does.

Helpful to know first

Comfort with algebra: solving for a variable, rearranging formulas, and working with proportions
Scientific notation and significant figures, including multiplying and dividing very large and very small numbers
Unit conversion by cancelling units (dimensional analysis)
Basic atomic structure: protons, neutrons, electrons, and what an atomic number and mass number mean

Questions

My child understands the concepts but keeps getting stoichiometry problems wrong. What is going on?: Almost always the conversion path, not the chemistry. The three-step grams to moles to moles to grams route has to be set up before any calculating, and students who start typing numbers into a calculator immediately lose track of which substance each figure belongs to. Sessions focus on writing the plan out first.
Does chemistry require more maths than biology?: Yes, noticeably. Moles, molarity, gas laws, and percent yield all involve multi-step calculation with units attached. Students who are shaky on rearranging equations or on scientific notation tend to struggle in chemistry even when they follow the ideas well.
How do you help with memorising polyatomic ions?: Through recall practice in conversation rather than a list to stare at. Evelyn Tutor asks for formulas and charges at intervals during other work, so nitrate, sulfate, and carbonate come up repeatedly while solving naming and stoichiometry problems.
Can this help without access to a lab?: It covers the calculation, notation, and reasoning parts of the course, and can talk through the purpose and expected results of standard experiments such as titrations or a hydrate mass-loss lab. It does not replace hands-on lab time or supervise practical work.