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.

M.4HSTP.36.a

Find the expected payoff for a game of chance. (e.g., Find the expected winnings from a state lottery ticket or a game at a fast food restaurant.)

Example Problems

A simple coin‑flip wager costs $5 to play. If the coin lands heads, the player receives $12 (net gain +$7); if it lands tails, the player receives nothing (net gain –$5).

Let

X

represent the player's net gain on one flip.
Calculate the expected net gain

E(X)

.

A charity conducts a raffle selling exactly 1,000 tickets at $5 each. Prizes are allocated as follows: one $1,000 prize, ten $50 prizes, and twenty $20 prizes. Each ticket can win at most one prize.

Let

X

represent the net gain for a person holding a single ticket (remember to subtract the $5 ticket cost).
Calculate the expected net gain

E(X)

.

A carnival booth offers a card‑draw game. A player pays

\$2

and draws one card at random from a standard 52‑card deck:

• Drawing an Ace wins

\$10

.
• Drawing any face card (Jack, Queen, or King) wins

\$4

.
• All other cards win nothing.

Let

X

represent the player's net gain on one draw.
Calculate the expected net gain

E(X)

.

Khan Academy Resources

Find expected payoffs Expected payoff example: lottery ticket Expected payoff example: protection plan

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