Embedded Files
Lesson Video
Lesson Video
Focus Standards
Focus Standards
Learning Focus
Learning Focus
Additional Resources
Additional Resources
A Develop Understanding Task
Explores compass and straightedge constructions, such as constructing a rhombus and square, which include smaller constructions, such as copying a line segment, copying an angle, constructing an angle bisector, and constructing a perpendicular line through a given point.
Construct a rhombus, a perpendicular bisector, and a square using only a compass and a straightedge (unmarked ruler) as tools.
How do I use geometric objects, such as circles and lines, to construct geometric figures like rhombuses and squares, rather than using measurement tools, such as rulers and protractors, to draw such figures?
A Solidify Understanding Task
Examines the construction of a parallelogram and an equilateral triangle, along with inscribing a hexagon, triangle, and square in a circle. Embedded in these constructions are skills such as constructing a parallel line through a given point, copying an angle, and copying a line segment.
Construct parallel lines and inscribed regular polygons.
How do I use geometric objects, such as circles and lines, to construct geometric figures like parallel lines and regular polygons, rather than using measurement tools, such as rulers and protractors, to draw such figures?
A Develop Understanding Task
Describing a sequence of transformations that will carry congruent images onto each other.
Show two figures are congruent based on an efficient and consistent sequence of rigid transformations.
How do I know if two images, such as the frog and lizard images of previous tasks, are congruent?
Is there a “best” sequence of transformations for showing that two figures are congruent to each other? What features of the figures themselves support this work?
Is there a sequence of transformations that would by easy to replicate every time?
A Solidify Understanding Task
Formally establishes the ASA, SAS, and SSS criteria for congruent triangles through experimentation, followed by justification and proof.
Explore and justify triangle congruence criteria using rigid transformations.
What do I need to know about two triangles before I can say that they are congruent?
How do I verify that a set of criteria that seems to imply triangles are congruent will always work?
A Practice Understanding Task
Practices identifying congruent triangles within other geometric figures and determines which criteria, ASA, SAS, or SSS, can be used to justify claims.
Identify congruent triangles, and write congruency statements.
Use triangle congruence criteria to justify other properties of geometric figures.
How can I capture what I see when I identify congruent triangles in symbolic notation?
How do I use the triangle congruence criteria to justify other properties of geometric figures?
When might it be helpful to decompose a geometric figure into triangles so that I can use triangle congruence criteria to prove something else about the figure?
A Practice Understanding Task
Examines justifications as to why compass and straightedge constructions produce desired results using properties of quadrilaterals, corresponding parts of congruent triangles, and the definitions of rigid-motion transformations.
NC.M2.G-CO.8
Justify construction strategies.
How can I explain why particular constructions (made only with lines and circular arcs) work?
How might I draw upon triangle congruence criteria and the definitions of rigid transformations in my explanations?
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