Misconception library

100 misconceptions, explained in 36 seconds each.

Each animation targets one specific wrong idea that students commonly hold. Watch the video, then try the interactive lesson. Free and open (CC BY 4.0).

Mathematics

Why does minus move right?

math-func-horizontal-shift

Which decimal is bigger?

math-larger-number-larger-digits

Can subtraction swap?

math-addition-commutative-subtraction

Can a product shrink?

math-frac-multiply-bigger

36s · 3-5, 6-8

Different names, same size

math-frac-equivalent-bigger

Regroup without changing value

math-frac-mixed-number-add

36s · 3-5, 6-8

Keep the equation balanced

math-alg-solve-undo

Combine only like terms

math-alg-like-terms

36s · 6-8, 9-12

Order negative numbers

math-int-ordering

Perimeter is a walk

math-meas-perimeter-count-squares

Plus moves left?

math-func-horizontal-shift-neg

Big shift, same rule

math-func-horizontal-shift-large

Tenths versus hundredths

math-decimal-compare-tenths-hundredths

36s · 3-5, 6-8

Do trailing zeros matter?

math-decimal-zeros-dont-matter

Does order matter with big numbers?

math-subtraction-order-large

Can subtraction go below zero?

math-subtraction-negative-result

A third of a half

math-frac-multiply-thirds

36s · 3-5, 6-8

Two thirds of three quarters

math-frac-multiply-two-thirds

Two quarters equal one half

math-frac-equivalent-quarters

Three sixths equal four eighths?

math-frac-equivalent-eighths

36s · 3-5, 6-8

Regroup with fifths

math-frac-regroup-fifths

36s · 3-5, 6-8

Five sixths plus five sixths

math-frac-regroup-sixths

Subtract first, then divide

math-alg-balance-subtract-first

36s · 6-8, 9-12

Two steps, both sides

math-alg-balance-two-step

Different coefficients, same variable

math-alg-like-terms-coefficients

36s · 6-8, 9-12

x and x² are not alike

math-alg-like-terms-squared

Close to zero matters

math-int-ordering-close-zero

Negative versus positive

math-int-ordering-mixed

Perimeter of a long rectangle

math-meas-perimeter-vs-area-rect

36s · 3-5, 6-8

Perimeter of a square

math-meas-perimeter-square

Vertical shift up

math-func-vertical-shift-up

Reflection across x-axis

math-func-reflection-x

Whole number versus decimal

math-decimal-whole-vs-decimal

Subtracting zero

math-subtraction-zero-identity

36s · K-2, 3-5

Whole number times a fraction

math-frac-multiply-whole-fraction

Solving with negatives

math-alg-balance-negative

Perimeter of a triangle

math-meas-perimeter-triangle

Absolute value and order

math-int-absolute-value-order

Ratios are multiplicative

math-ratio-additive

Cross multiplication

math-proportional-cross-multiply

Decimals and fractions are the same thing

math-decimal-fraction-conversion

36s · 3-5, 6-8

Negative times negative

math-int-negative-multiplication

36s · 6-8, 9-12

Larger minus smaller always?

math-subtraction-larger-from-smaller

36s · 3-5, 6-8

Simplifying doesn't change value

math-frac-simplify-means-smaller

36s · 3-5, 6-8

Distribution over addition

math-alg-distribute-addition

36s · 6-8, 9-12

Improper fractions to mixed numbers

math-frac-improper-to-mixed

36s · 3-5, 6-8

Circumference of a circle

math-meas-circumference

Ordering unit fractions

math-frac-unit-fractions-order

Regroup with halves

math-frac-regroup-halves

Constants are like terms

math-alg-like-terms-constants

Steeper line = larger slope

math-func-slope-steepness

Percent, fraction, decimal equivalence

math-percent-fraction-decimal

Variables can vary

math-alg-variable-unknown

36s · 6-8, 9-12

Area is not perimeter

math-area-perimeter-confusion

36s · 3-5, 6-8

Physics

Does heavier fall faster?

phys-heavier-falls-faster

36s · 6-8, 9-12

Air slows everything equally

phys-air-resistance-same-as-gravity

No force means no motion?

phys-force-implies-motion

36s · 6-8, 9-12

Force means speed?

phys-bigger-force-bigger-speed

Heat and temperature are different

phys-heat-is-temperature

36s · 6-8, 9-12

Boiling means getting hotter?

phys-boiling-means-hotter

Terminal velocity

phys-terminal-velocity

Horizontal and vertical are independent

phys-projectile-independence

Action-reaction don't cancel

phys-action-reaction-cancel

Circular motion needs inward force

phys-circular-motion-force

Cold is not a substance

phys-cold-is-energy

Everything reaches the same temperature

phys-thermal-equilibrium

36s · 6-8, 9-12

Energy is not used up

phys-energy-used-up

36s · 6-8, 9-12

Gravity changes with altitude

phys-gravity-varies-altitude

Friction is not always bad

phys-friction-always-bad

Insulation does not add heat

phys-insulation-adds-heat

Weight is not mass

phys-weight-vs-mass

36s · 6-8, 9-12

Weight vs. gravitational acceleration

phys-weight-makes-objects-fall

Temperature measures average KE

phys-temperature-measures-heat

Biology

Cell membrane is not a wall

bio-cell-membrane-wall

36s · 6-8, 9-12

Which way does water flow?

bio-osmosis-direction

Evolution has no goal

bio-evolution-goal

Evolution is not a ladder

bio-evolution-ladder

Where do plants get food?

bio-plants-eat-soil

Plants breathe CO₂?

bio-plants-breathe-co2

36s · 6-8, 9-12

Moving against the gradient

bio-active-transport

Cell wall versus cell membrane

bio-cell-wall-vs-membrane

Fittest ≠ strongest

bio-survival-fittest-strongest

Acquired traits are not inherited

bio-acquired-traits-inherited

The photosynthesis equation

bio-photosynthesis-equation

36s · 6-8, 9-12

Photosynthesis isn't only in leaves

bio-photosynthesis-only-in-leaves

Ecosystems are not static

bio-ecosystem-balance-static

36s · 6-8, 9-12

Cells can swallow things

bio-endocytosis

Vestigial structures are evidence of evolution

bio-vestigial-structures

Not all light colors work equally

bio-photosynthesis-light-color

Diffusion is passive

bio-diffusion-requires-energy

36s · 6-8, 9-12

Chemistry

Where does mass go when wood burns?

chem-mass-lost-burning

36s · 6-8, 9-12

Does dissolving destroy mass?

chem-mass-dissolving

Electrons are not tiny planets

chem-electrons-orbit-like-planets

Atoms are mostly empty

chem-atoms-are-solid-spheres

36s · 6-8, 9-12

Rusting gains mass?

chem-rusting-gains-mass

36s · 6-8, 9-12

chem-gas-has-mass

Protons determine the element

chem-protons-determine-element

36s · 6-8, 9-12

Not all isotopes are radioactive

chem-isotopes-radioactive

Chemical vs physical change

chem-chemical-vs-physical

Electron shells and stability

chem-electron-shells-full