Study Guide — HSG.CO.A.1
Know precise definitions of angle, circle, perpendicular line, parall…
Use transformations and rigid motions to prove figures are congruent.
What this standard means
- Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc.
- Apply know precise definitions of angle, circle, perpendicular line, parall… with models and explanation
- Describes transformations precisely
_See printable PDF for diagram._
How to use the 20 practice sets
| Sets | When to use | | --- | --- | | 1–5 | Intro — explore together, short written items | | 6–10 | Core skills — diagrams and written practice | | 11–15 | Mixed review — explain thinking | | 16–20 | Stretch — word problems and mastery tasks |
Pacing: 10–15 minutes per session.
How to practice
1. Name the transformation sequence 2. Mark corresponding parts on diagrams 3. State which congruence criterion applies
_See printable PDF for diagram._
Common mistakes
- Assuming congruence without justification
- Wrong correspondence of vertices
Review and practice tests
1. Start Review 1/10 when sets 1–3 feel comfortable. 2. Move up one review level with little help. 3. Use Practice Test 4/10–6/10 for mid-standard checks. 4. Practice Test 10/10 is the mastery bar for HSG.CO.A.1.
- [ ] Describes transformations precisely
- [ ] Uses congruence criteria correctly
- [ ] Completes logical proof steps
Materials for this standard
- Practice Problems — 20 printable sets
- Review — 10 difficulty levels
- Practice Test — 10 difficulty levels
- Answer key — for parents and tutors