Class 8 common misconceptions

Do factors always come in different pairs? — Tempting mistake: “Every number has an even number of factors.”

1 worked visual example · 8 “If your child says…” checks

What does an exponent count? — Tempting mistake: “2³ = 6”

1 worked visual example · 8 “If your child says…” checks

Does an extra digit always make a number larger? — Tempting mistake: “IX is larger than X because IX has two symbols.”

1 worked visual example · 8 “If your child says…” checks

Is one pair of parallel sides enough for a parallelogram? — Tempting mistake: “A quadrilateral with one pair of parallel sides is a parallelogram.”

1 worked visual example · 8 “If your child says…” checks

Can a pattern of examples establish a number rule? — Tempting mistake: “If n² + n + 41 is prime for the first several whole numbers, it must always be prime.”

1 worked visual example · 8 “If your child says…” checks

Does the outside factor reach both terms? — Tempting mistake: “3(x + 2) = 3x + 2”

1 worked visual example · 8 “If your child says…” checks

Does adding the same amount preserve a recipe? — Tempting mistake: “A 2:3 syrup-to-water ratio stays the same at 3:4.”

1 worked visual example · 8 “If your child says…” checks

Does a percent already give a count? — Tempting mistake: “A 25% discount always means 25 rupees off.”

1 worked visual example · 8 “If your child says…” checks

Can the theorem be used on any triangle? — Tempting mistake: “For two sides 3 cm and 4 cm, the third side must be 5 cm.”

1 worked visual example · 8 “If your child says…” checks

Do more workers always take more time? — Tempting mistake: “If workers double, the time for a fixed task doubles.”

1 worked visual example · 8 “If your child says…” checks

Can a boundary grow when its individual segments get shorter? — Tempting mistake: “A Koch-curve step shortens the boundary because every replacement segment is shorter.”

1 worked visual example · 8 “If your child says…” checks

Can the average come from just the smallest and largest values? — Tempting mistake: “The mean of 2, 2, 2 and 10 is 6.”

1 worked visual example · 8 “If your child says…” checks

Can you square a sum term by term? — Tempting mistake: “(x + 3)² = x² + 9”

1 worked visual example · 8 “If your child says…” checks

Which side is the height of a slanted parallelogram? — Tempting mistake: “Multiply the base by the slanted side to find area.”

1 worked visual example · 8 “If your child says…” checks

Does a difference in one trial establish a reliable effect? — Tempting mistake: “Setup B always evaporates more water because it lost 5 mL while setup A lost 4 mL in the first trial.”

1 worked visual example · 8 “If your child says…” checks

Are all microbes harmful? — Tempting mistake: “All bacteria make people ill.”

1 worked visual example · 8 “If your child says…” checks

Do antibiotics treat viral infections? — Tempting mistake: “An antibiotic kills the virus that causes a cold.”

1 worked visual example · 8 “If your child says…” checks

Does insulation remove the current in a wire? — Tempting mistake: “A coated wire cannot produce a magnetic effect.”

1 worked visual example · 8 “If your child says…” checks

Does a push have to cause motion? — Tempting mistake: “There is no force on a box that stays still while I push it.”

1 worked visual example · 8 “If your child says…” checks

Does the same force always create the same pressure? — Tempting mistake: “A sharp and blunt end press equally because I use the same force.”

1 worked visual example · 8 “If your child says…” checks

Do particles themselves expand when a gas expands? — Tempting mistake: “Heating a gas makes each molecule bigger.”

1 worked visual example · 8 “If your child says…” checks

Is a uniform mixture a compound? — Tempting mistake: “Salt water is a compound because it looks uniform.”

1 worked visual example · 8 “If your child says…” checks

Does a dissolved solid disappear from the mass? — Tempting mistake: “When sugar dissolves, it stops adding to the mass.”

1 worked visual example · 8 “If your child says…” checks

Why do mirror images look reversed? — Tempting mistake: “A plane mirror swaps left and right in space.”

1 worked visual example · 8 “If your child says…” checks

Does the Moon itself change shape? — Tempting mistake: “The Moon physically gets thinner during a crescent phase.”

1 worked visual example · 8 “If your child says…” checks

Do aquatic animals need oxygen? — Tempting mistake: “Fish have no need for oxygen because they live underwater.”

1 worked visual example · 8 “If your child says…” checks

Does being closer to the Sun always make a planet hotter at its surface? — Tempting mistake: “Mercury must have a hotter average surface than Venus because it is closer to the Sun.”

1 worked visual example · 8 “If your child says…” checks