Watch the proof come alive! Students see how dots arrange into triangles and pair up to form rectangles, revealing why T(n) = n(n+1)/2. Students control an 8-phase animated walkthrough with 10 worked examples, an interactive scrubber timeline, and clickable step-by-step panels.

Perfect for visual learners who need to SEE why the math works, not just memorize formulas.

What's Included:
- 10 worked examples with varying values
- 8-step animated proof walkthrough per example
- Interactive scrubber/timeline (play, pause, click any step)
- Step-by-step explanation panel with equations
- Keyboard navigation support

How It Works:
- Open the HTML file in any browser (Chrome, Edge, Firefox, Safari)
- Works on Chromebooks, laptops, tablets, and desktops
- No internet required after download
- No installation, no login, no app needed
- Zero prep - just share the file and go

Skills Covered:
- Understanding why summation formulas work (not just memorizing them)
- Connecting visual dot patterns to algebraic expressions
- Number pattern exploration and figurate numbers
- Pre-algebra enrichment and number theory foundations

Grade Level: 6th - 9th Grade

Great for introducing summation formulas, number pattern exploration, pre-algebra enrichment, sub plans and independent work, and flipped classroom pre-lessons!

New to HTML Learning Resources?
We highly recommend checking out our free guide: How to Use and Understand HTML File Learning Resources. It walks you through everything you need to know about using interactive HTML activities in your classroom.