Tutor Sheet: Grades 9–12 Science (US)

Targets: HS Physics/Chem/Bio/Earth high-yield misconceptions

Physics

[FBD] Free-Body Diagrams

• Check: “A box is pushed at constant speed—draw forces.” (Expect only 2: push & friction? No—should be 3: push, friction, weight, with normal; net force zero.)
• Fix: Four-force checklist: weight ↓, normal ↑, push/ tension →, friction ←; net-force statement.

[VectorComp] Components & signs

• Check: A 10 N force at 30° above +x → find x/y components.
• Fix: Sketch quadrant; Fx=Fcos⁡θF_x=F\cos\thetaFx​=Fcosθ, Fy=Fsin⁡θF_y=F\sin\thetaFy​=Fsinθ; sign from quadrant before numbers.

[CircuitUnits] Ohm/Kirchhoff

• Check: In a series circuit, where is current largest? (trap: “first bulb”).
• Fix: State rule: series → same I everywhere; parallel → same V across branches. Use one KCL example.

[OpticsSigns] Lenses/mirrors

• Check: For a converging lens with object beyond 2f—image type/side/size?
• Fix: Ray-rule sketch (parallel→focus; through center straight); sign table next to diagram.

Chemistry

[MoleRatio] Stoichiometry

• Check: “How many moles of O₂ to burn 2 mol CH₄?” (Expect 4 mol.)
• Fix: Balance first; use coefficient ratio before masses.

[LeChatelier] Qualitative equilibrium

• Check: “Increase pressure for N₂ + 3H₂ ⇌ 2NH₃—shift?”
• Fix: Count gas moles LHS/RHS; fewer moles favored under ↑P; connect to particle picture.

[pH≠Strength] Strength vs pH

• Check: “0.01 M acetic acid vs 0.01 M HCl—same strength?”
• Fix: Distinguish strong/weak (extent of ionization) vs concentration; give conductivity demo cue.

[RedoxBook] Bookkeeping electrons/charge

• Check: Balance MnO₄⁻ + Fe²⁺ in acidic solution (watch for charge errors).
• Fix: Half-reaction method: atoms → charge (H⁺/H₂O, e⁻) → multiply → add → check charges.

Biology

[Allele≠Trait] Terms

• Check: Define gene/allele/trait; Aa × Aa → genotype vs phenotype ratios.
• Fix: Three-tier definitions + 2×2 Punnett with labels; link to protein/trait.

[MeiosisSeg] Meiosis timing

• Check: “When do homologs vs sister chromatids separate?”
• Fix: Meiosis I = homologs (reduction); Meiosis II = sisters; quick stage sketch.

[Teleology] Need-based evolution

• Check: “Giraffes grew long necks because they needed to reach leaves—agree?”
• Fix: Selection frame: variation → differential survival/reproduction → allele frequency change.

[EnergyPyramid] Trophic efficiency

• Check: “If producers have 10,000 J, estimate secondary consumer energy.”
• Fix: 10% law ladder; discuss reasons (respiration, heat loss).

Earth/Space

[Wx≠Clim] Weather vs climate

• Check: “It snowed today, so global warming is false—evaluate.”
• Fix: Define climate as long-term stats; show 30-year normals vs daily variability.

[Ozone≠GHG] Ozone vs greenhouse

• Check: “Ozone hole causes global warming—true?”
• Fix: Contrast roles: stratospheric O₃ blocks UV; greenhouse gases trap IR.