First half — proofs + congruence + similarity (~14–15 años)
Highest bar · 🇺🇸 Estados Unidos
Razonamiento formal (two-column / paragraph / flow proof), líneas y ángulos con teoremas, congruencia formal (SSS, SAS, ASA, AAS, HL), triángulos y cuadriláteros con propiedades demostradas, similitud completa con criterios AA/SAS/SSS y factor de escala k/k²/k³.
| Country | Expected topics | Official source |
|---|---|---|
| 🇺🇸Estados Unidos | G-CO (Congruence): definir vía rigid motions, derivar SSS/SAS/ASA, demostrar theorems clásicos. G-SRT (Similarity): definir vía dilatación, AA/SAS/SSS de similitud. Two-column proof formal. | CCSS-M HS Geometry ↗ |
| 🇸🇬Singapur | Sec 3 Express: congruence y similarity con applications, propiedades de cuadriláteros, geometric reasoning. | Singapore MOE Lower Secondary Mathematics Syllabus (Express) ↗ |
| 🇬🇧Reino Unido | GCSE Higher: criterios formales de congruencia, similarity con scale factor incluido k² y k³, proofs informales. | UK GCSE Mathematics Subject Content ↗ |
| 🇦🇺Australia | Year 9-10A: congruence y similarity con razonamiento deductivo. Geometric proofs introducidas. | ACARA Australian Curriculum Mathematics Year 9-10 v9.0 ↗ |
Rodybee skills at this grade
Formal geometry notation · Conditional statements · Inductive vs deductive reasoning · Two-column proof · Paragraph proof · Flow proof · Prove: vertical angles theorem · Prove: parallels & transversal · Prove: perpendicular bisector · Prove: triangle sum 180° · Exterior angle theorem · Congruence — rigid motion definition · Congruence — SSS · Congruence — SAS · Congruence — ASA / AAS · Congruence — HL (right triangle) · Apply congruence in a proof · Isoceles base angles · Midsegment theorem · Parallelogram properties (proof) · Rectangle / rhombus / square (proof) · Trapezoid properties · Similarity — dilation definition · Similarity — AA · Similarity — SAS / SSS · Triangle proportionality · Scale factor (k, k², k³) · Apply similarity in a proof