Free math for everyone — in English and Filipino.
Built on the flipped classroom: video lessons from Dr. E's real classroom, a free worksheet for every lesson, and a research-tested model teachers can use to flip their own class.
Libreng math para sa lahat — sa English at Filipino.
Start learning — free, in English and Filipino
Short video lessons, free worksheets with answer keys, and no login, ever.
Where do I start?
Not sure which course fits you? Find your starting point.
Try a free lesson
Watch a short clip, follow a worked example, then solve one yourself.
DepEd Math, Grades 7–12
Lessons for every grade, aligned to MATATAG, in English and Filipino.
AP Exam Prep
AP Calculus AB and AP Statistics: lessons, worksheets and original FRQ practice.
Free worksheets
569 printable worksheets with answer keys, each paired with a video lesson.
Test prep
Practice for LET, UPCAT, SAT and more, and earn badges as you go.
Flip your class with a model that works
Dr. E has flipped math classes since 2012, from Barstow High School to community college. Start with the free guide, then bring in the tools.
Flipped Classroom Guide
Dr. E's method for flipping a math class, from the first unit to the research.
Teach It Like You Stream It
Bring a creator's energy and simple video tools into your online classroom.
Numberbender Studio
Your camera and slides side by side, shared straight into Zoom, Meet or Teams. Free, no login.
Teacher resources
Worksheets with answer keys, starter kits and guides, free to download and assign.
DepEd teacher pages
Ready-to-assign lessons for Grades 7–12, with answer keys.
Workshops for your school
Workshops, keynotes and ongoing PD from Dr. E for schools, colleges and districts.
How the flipped classroom works
The model Dr. E has taught and tested since 2012 — free for any teacher to use.
- 1
Watch at home
Students watch a short video lesson before class — in English or Filipino — pausing and replaying as often as they need.
- 2
Practice in class
Class time goes to solving problems together, with the free worksheet for that lesson and the teacher right there to help.
- 3
Check and close gaps
Quick checks and answer keys show what students have mastered, so the teacher can spend time where it's needed most.
Tested in a real classroom. In Dr. E's 2016 randomized controlled trial with 91 high school algebra students, the flipped model produced significant performance gains. Published by Springer and cited 60 times.
Our latest work — Fall 2026
What Numberbender has been building, and where Dr. E is taking free, bilingual math next.
Teach It Like You Stream It is going to SXSW EDU 2027
Dr. E's session, Broadcast Teaching for $0, is on the SXSW EDU schedule in Austin, March 13–16, 2027 — taking free, streaming-style teaching to one of education's biggest stages.
Read the story →AP Exam Prep is live
Free AP Calculus AB and AP Statistics review: lessons by AP unit, worksheets, and original FRQ practice with full solutions.
Start reviewing → Talk · Oct 2026Presented at EDUCAUSE 2026
An online session on bringing presence and energy to Zoom and Google Meet classes, with the free Numberbender Studio.
Read the recap → New · Term 2Math 9, week by week
A page for every week of DepEd Term 2, with lessons in English and Filipino and a worksheet for each one.
See this week's lesson →
Dr. Peter Esperanza — Math Professor & Online Educator
Dr. E built his flipped math classroom at Barstow High School, starting in 2012 — along with the research behind it and, eventually, the YouTube channel. After 14 years at the high school, he brought the model to Barstow Community College, where he teaches today.
He founded Numberbender on a simple belief: great math instruction should be free and available to anyone — student or teacher, anywhere in the world. His video lessons have been viewed more than 16 million times.
Learn more about Dr. E →
Trusted by students, educators, and institutions
Numberbender's reach spans social platforms, college campuses, and conference stages.
I transferred to Barstow High as a new student, and Dr. E's videos rebuilt my confidence in math. Then he had me create AP Calculus and AP Statistics videos of my own — I got to learn math twice, and scored a 5 on both AP exams. That's an experience I'll cherish forever.
I was hesitant to record my first video — it always felt awkward and I cringed watching myself back. Dr. E told me to focus on the students in my classroom and ignore the noise of who else might watch, and that one shift unlocked it. I found a skill I never thought I could do.
Support free math for everyone — add your name.
Numberbender is a nonprofit making math free for every student and teacher, in English and Filipino. Adding your name costs nothing, and it's how we show schools, partners and funders that free, bilingual math matters.
- Free — no donation needed
- Dr. E emails you when new lessons and worksheets are ready
- Your answers show us who is being left out, and where to build next
Every worksheet is already free to download, no sign-up needed: browse the free bundles.
You're counted. Dr. E will email you when new lessons and worksheets are ready.
Browse the free worksheet bundles →