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.

MIII.G-MG.A.2

Apply concepts of density based on area and volume in modeling situations (e.g., persons per square mile, BTUs per cubic foot).

Example Problems

Consider the following problem:
A savings account balance is growing at a rate of

r(t) = 200e^{0.03t}

dollars per year (where

t

is the time in years). At year

t = 2

, the balance is $5,500. How much money will be in the account at year

t = 6

?

Write an expression that can be used to solve the problem.

Consider the following problem:
An oil tank is being drained, and the volume of oil remaining is changing at a rate of

r(t) = -120 + 8t

liters per hour (where

t

is the time in hours). At time

t = 1

hour, 9,000 liters remain. What volume of oil remains at

t = 4

hours?

Write an expression that can be used to solve the problem.

Consider the following problem:
The number of people in a cafeteria is changing at a rate of

r(t) = 1920 - 160t

people per hour (where

t

is the time in hours). At time

t = 11.5

, there were 60 people in the cafeteria. How many people were in the cafeteria at hour

t = 12.5

?

Write an expression that can be used to solve the problem.

Khan Academy Resources

Density word problems

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