Is Goblins free for teachers?

Yes. Goblins offers a generous free tier that includes 1 live feedback assignment per week, insights on student mastery and replays, and the ability to upload your own content. The Max plan adds unlimited assignments, superadaptive mode, grade exports, standards growth reports, and SSO/LMS integration, with per-student pricing for schools and districts.

How does Goblins work?

Three simple steps: (1) Share an assignment from thousands of standards-aligned topics using a share code. (2) Students speak and draw their thinking naturally, and Goblins responds with Socratic questioning that sounds just like their teacher. (3) Teachers get real-time formative insights showing what students struggle with and suggestions to inform instruction.

Does Goblins prevent cheating?

Yes. Goblins uses a purpose-trained AI model that evaluates cheating signals in real time. It can detect when students are copying answers, using external tools inappropriately, or not genuinely working through problems. Copy-pasting answers is also blocked.

Can I use my own voice with Goblins?

Yes. Teachers can record their voice and take a selfie to create a custom 3D avatar in about 30 seconds. Students then hear help in their own teacher's voice and see a familiar face, making the experience more personal and effective.

What math levels does Goblins cover?

Goblins covers math from Grade 5 through AP Calculus, including thousands of standards-aligned topics. Teachers can also upload their own content for custom assignments at any level.

Is Goblins FERPA compliant?

Yes. Goblins is FERPA and state compliant. Student data privacy and security are a top priority.

Does Goblins support English Language Learners?

Yes. Goblins supports 30+ languages so teachers don't have to translate every worksheet. It is especially helpful for ELL students who need accessible math instruction in their native language.

G-SRT.B.5

Use congruence and similarity criteria for triangles to solve problems and to prove relationships in geometric figures.

Example Problems

Polygon Y has an area of 11 square units. Celia drew a scaled version of Polygon Y using a scale factor of 3 and labeled it Polygon Z.
What is the area of Polygon Z?

Polygon V has an area of

1

square unit. Jun-seo drew a scaled version of Polygon V using a scale factor of

7

and labeled it Polygon W.
What is the area of Polygon W?

Polygon O has an area of

98 \text{ square units}

. Hana drew a scaled version of Polygon O using a scale factor of

\frac{1}{7}

and labeled it Polygon P. What is the area of Polygon P?

Khan Academy Resources

Triangle similarity review Triangle congruence review Determine congruent triangles Find angles in congruent triangles Solve triangles: angle bisector theorem Determine similar triangles: Angles Special right triangles Determine similar triangles: SSS Solve similar triangles (basic)Solve similar triangles (advanced)Use similar triangles Prove triangle similarity Justify constructions Use ratios in right triangles Find angles in isosceles triangles Prove triangle properties Prove parallelogram properties Prove triangle congruence Determining congruent triangles Geometry proof problem: congruent segments Geometry proof problem: midpoint Isosceles & equilateral triangles problems Finding angles in isosceles triangles (example 2)Finding angles in isosceles triangles Corresponding angles in congruent triangles Triangle similarity postulates/criteria Solving similar triangles Determining similar triangles Solving similar triangles: same side plays different roles Challenging similarity problem Using similar & congruent triangles 30-60-90 triangle example problem Using the angle bisector theorem Geometry proof problem: squared circle Proving the SAS triangle congruence criterion using transformations Proving the SSS triangle congruence criterion using transformations Calculating angle measures to verify congruence Geometry word problem: Earth & Moon radii Geometry word problem: a perfect pool shot Proving the ASA and AAS triangle congruence criteria using transformations Proving triangle congruence Geometry word problem: the golden ratio

1-on-1 AI tutoring aligned to G-SRT.B.5. Instant help for students, real-time insights for teachers.

Used in classrooms by 100,000+ students at Baltimore County, Plano ISD, Deer Valley USD, KIPP, and districts nationwide.

Free for teachers, forever →