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 F-TF taught?

This standard is part of the F-TF curriculum in Alaska Mathematics Standards.

F-TF: Trigonometric Functions

Trigonometric Functions

Print

Trigonometric Functions introduces radian measure, the unit circle, and the six trigonometric functions as tools for modeling periodic phenomena. Graphs of sine, cosine, and tangent are analyzed for amplitude, period, and phase shift. Pythagorean and other identities are proved and applied, including addition and subtraction formulas at advanced levels.

F-TF.1Understand radian measure of an angle as the length of the arc on the unit circle subtended by the angle.F-TF.2Explain how the unit circle in the coordinate plane enables the extension of trigonometric functions to all real numbers, interpreted as radian measures of angles traversed counterclockwise around the unit circle.F-TF.3(+) Use special triangles to determine geometrically the values of sine, cosine, tangent for π/3, π/4 and π/6, and use the unit circle to express the values of sine, cosines, and tangent for π-x, π +x, and 2π –x in terms of their values for x, where x is any real number.F-TF.4(+) Use the unit circle to explain symmetry (odd and even) and periodicity of trigonometric functions.F-TF.5Choose trigonometric functions to model periodic phenomena with specified amplitude, frequency, and midline.F-TF.6(+) Understand that restricting a trigonometric function to a domain on which it is always increasing or always decreasing allows its inverse to be constructed.F-TF.7(+) Use inverse functions to solve trigonometric equations that arise in modeling contexts; evaluate the solutions using technology, and interpret them in terms of the context.F-TF.8Prove the Pythagorean identity sin^2(θ) + cos^2(θ) = 1 and use it to calculate trigonometric ratios.F-TF.9(+) Prove the addition and subtraction formulas for sine, cosine, and tangent and use them to solve problems.

Example Problems

Find the exact value:

\cos(\pi)

Integrate:

\int 9\sin(x) dx

Find the exact value:

\cos(90°)

Determine the period of the following:

y = -3\sin(5x - 2)

Give an exact value.

Let

g(x) = \sec(x)

.
Find

g'(\frac{\pi}{3})

.

1-on-1 AI tutoring aligned to F-TF. 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 →