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.

What grade level is G-CO taught?

This standard is part of the G-CO curriculum in Massachusetts Curriculum Framework for Mathematics.

G-CO: Geometry - Congruence

Geometry - Congruence

Print

Congruence defines transformations precisely: translations, rotations, reflections, and their compositions. Standards include proving triangle congruence criteria using rigid motions and making formal constructions with compass and straightedge. This domain is the proof-based core of Geometry.

G-CO.AExperiment with transformations in the plane.G-CO.BUnderstand congruence in terms of rigid motions.G-CO.CProve geometric theorems and, when appropriate, the converse of theorems.G-CO.DMake geometric constructions.

Example Problems

Point Q'

(2, 5)

is the image of Q

(-1, 1)

under a translation.
What was the translation?

Two sides of a triangle have the following measures:
46 and 15

Find the range of possible measures for the third side:

x

Write the equation of a line that is parallel to

y = -7x + 5

and that passes through the point

(3, -2)

.

1-on-1 AI tutoring aligned to G-CO. 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 →