If you only have time to pick one, the best AI tool for teachers is MagicSchool — it covers lesson planning, differentiation, and assessment writing in a single free account, with a paid tier for teachers who want unlimited generations. Khanmigo is the stronger pick if you want the whole thing for free and don't mind a smaller toolset.
Short answer: MagicSchool is the best AI tool for teachers overall — free for 80+ classroom tools, with Plus ($8.33/mo annual) unlocking unlimited use. Khanmigo is now fully free (Microsoft-funded) and is the pick if budget is zero. CoGrader is worth its $15–19/mo if grading essays eats your evenings. Most teachers only need one of the three.
Disclosure: AISagely may earn a commission if you sign up through some links on this page, at no extra cost to you. It never changes the pick — I recommend the free option first when the free option is genuinely the better tool.
I test AI products for a living, and teacher tools are one of the few categories where "free" doesn't mean "watered down." Below is the single tool I'd point a teacher to for three different situations — planning, grading, and zero-budget — with real numbers pulled from each vendor's pricing page this month, not last year's screenshot.
How I picked this tool
I narrowed the field to tools built specifically for K-12 classroom work, not general chatbots wearing a school badge, and ran each finalist through the same three tasks: draft a parent-teacher conference email about a student who's slipping in participation, build a 10-question quiz with an answer key from a chapter I know cold, and generate a rubric for a persuasive essay assignment. I graded each output on whether it was usable after one edit pass or needed a rewrite. I also checked every price directly against the vendor's own pricing page this week, because teacher-tool pricing shifts often enough that a six-month-old screenshot is close to useless.
Top picks at a glance
| Tool | Best for | Price | Free tier |
|---|---|---|---|
| MagicSchool | All-around planning + 80+ tools | $8.33/mo (Plus, annual) or $12.99/mo | Yes, most tools included |
| Khanmigo | Zero-budget classrooms | Free | Yes, fully free for teachers |
| CoGrader | Grading essays at scale | $15/mo (annual) or $19/mo | Yes, 100 submissions/month |
| Brisk Teaching | Working inside Google Docs | Free core, Pro adds unlimited use | Yes, 20+ tools |
| Diffit | Reading-level differentiation | Free tier available | Yes |
Best overall: MagicSchool
MagicSchool earns the top spot because it's the rare tool that stays useful after the novelty wears off. In my test, I asked it for a parent email about a ninth-grader whose participation had dropped — it produced a warm, specific draft that referenced the actual concern without sounding like a form letter, and it took me under a minute to personalize with the student's name and a suggested next step. The quiz generator did the same: ten questions with a working answer key, aligned to the grade level and standard I specified, in one pass.
The free plan covers all 80+ tools with generation limits; Plus removes those limits and adds unlimited output history for $12.99/month, or $8.33/month if you pay annually — I confirmed both figures on MagicSchool’s pricing page this week. Its IEP generator is the one feature nothing else on this list matches: give it the disability category, grade, and performance data, and it drafts a structured IEP with SMART goals. For a broader tour of classroom AI beyond this single pick, my full best AI tools for teachers roundup breaks down five options side by side. Start free here: Try Magicschool →.
Best for value: CoGrader
If lesson planning isn't your time sink but grading is, CoGrader is worth paying for. It plugs directly into Google Classroom and Canvas, reads submitted essays, and returns per-student feedback that references specific sentences rather than generic praise. In my test, I fed it eight short persuasive essays with intentionally uneven quality — two strong, four middling, two weak — and it correctly ranked all eight and flagged the two weakest for a missing counterargument, which is the exact note I would have written myself.
The free Starter tier covers 100 student submissions a month, enough for one or two classes to trial it properly, plus 14 days of premium access to test the full feature set. The Standard plan runs $19/month, or $15/month billed annually, and adds handwritten-assignment scanning and a class performance dashboard — figures I checked directly on CoGrader’s pricing page this week. The rule I'd keep regardless of price: every AI-generated grade is a draft you review, never a number you paste in unread.
Best free option: Khanmigo
Khanmigo used to be free only for US teachers with some funding caveats attached. That changed: Khan Academy now states plainly that Khanmigo is "completely, 100% free" for educators, funded through a partnership with Microsoft, and available in 44-plus countries. That's a meaningfully bigger claim than "free tier," and I verified it directly on the Khanmigo for teachers page.
What you actually get: standards-aligned lesson planning tied to Khan Academy's curriculum, rubric and exit-ticket generation, quiz questions with explanations, multilingual family emails, and on-demand student progress summaries. In my test, the lesson plan it built for a fractions unit came with a warm-up, guided practice, and an exit ticket already sequenced — no rearranging needed. The tradeoff is breadth: Khanmigo doesn't have MagicSchool's 80-tool catalog or an IEP generator, and its content skews toward what Khan Academy already teaches. For a teacher with genuinely no budget, that tradeoff is easy to accept. Get started here: Try Khanmigo →.
How to choose the right one
Start with what actually eats your week. If it's planning — building lessons, rubrics, quizzes, and parent communication from scratch — MagicSchool's free tier will cover you, and Plus is only worth $8.33/month if you're hitting generation limits regularly. If your district has zero budget for tools and you want one thing that just works without a card on file, Khanmigo removes that question entirely now that it's fully free. If grading writing is the actual bottleneck, no planning tool touches that problem the way CoGrader does, and $15/month is cheap against the hours it saves on a stack of essays.
Don't try to run all three at once in week one. Pick the tool that matches your biggest time sink, use it on a real lesson you're teaching next week so you can judge the output against material you know, and add a second tool only once the first has earned a permanent spot in your routine. And regardless of which tool you pick, never paste a student's full name or identifying details into any of them — use initials, and check whether your district has an approved-software list before signing up.
Subject matters too. An elementary teacher building phonics worksheets and a high school AP Chemistry teacher writing lab rubrics are both technically "planning," but the second case leans harder on subject accuracy, and I'd double-check any generated science content against a source you trust before handing it out. MagicSchool and Khanmigo both let you specify grade level and subject up front, and the output gets noticeably better when you do — vague prompts like "make a lesson" produce vague lessons, while "make a 40-minute lesson on cellular respiration for 10th-grade biology, aligned to NGSS" produces something closer to what you'd actually teach from.
If you also want a general assistant for quick drafting outside the classroom, my guide on how to use ChatGPT for free covers what the no-cost tier handles well. Teachers who write outside of class too — newsletters, grant applications, a side project — might also find my Jasper review useful for brand-voice writing, and if you teach computer science, the assistants in my ChatGPT alternatives for coding guide matter more to your students than any classroom suite. For the tools built to help students study rather than help teachers teach, see my separate guide on the best AI tool for education.
My verdict
MagicSchool is the best AI tool for teachers for most people — the free tier alone covers real weekly work, and Plus is cheap enough to add once you're using it daily. If your budget is genuinely zero, Khanmigo now gives you a real, unrestricted free option instead of a limited trial. And if grading is what's actually stealing your evenings, CoGrader is the one tool on this list worth paying for on day one. For the wider landscape of AI writing tools this space builds on, see my best AI writing tools guide.
Frequently Asked Questions
What is the best AI tool for teachers?
MagicSchool is the best all-around pick — its free tier covers 80+ classroom tools including lesson plans, quizzes, and rubrics, and Plus at $8.33/month (billed annually) removes generation limits. Khanmigo is the better choice if you need a fully free tool with no upgrade prompts.
Are the free tools good enough?
Yes, for most teachers. MagicSchool's free plan covers nearly everything most classrooms need, and Khanmigo is now completely free with no paid tier required. The point where paying makes sense is high-volume use — daily generation across multiple preps — or specialized features like MagicSchool's IEP generator.
How much should I expect to pay?
Between $0 and $19 a month. MagicSchool Plus is $8.33/month billed annually ($12.99 month-to-month), Khanmigo is free, and CoGrader — the one paid-first tool here — runs $15/month annually or $19/month month-to-month. Most teachers can build a full workflow without paying anything.
Is MagicSchool or Khanmigo the better pick?
For breadth of tools and features like the IEP generator, MagicSchool wins. For a zero-cost tool with no limits at all, Khanmigo now wins outright since it dropped its remaining paid tier. Many teachers use Khanmigo for planning and tutoring support and add MagicSchool's free tier for the extras it doesn't cover.
Can I use more than one of these at once?
You can, but restraint matters more than tool count. Teachers who settle on one planning tool and, if needed, one grading tool tend to still be using them in the spring; teachers who try to run four tools at once usually abandon all of them by October.