Chris Spackman's NeoCities Page

Welcome to Chris Spackman's NeoCities page

I loved GeoCities back in Japan in the 1990s, so was thrilled to discover NeoCities. I'm using this site mostly for fun activities and javascript experiments that I make for my schools and classes and for other teachers or students.

Please don't hesitate to email me at chris@chrisspackman.com with bug reports, suggestions for improvements, or requests for other teacher-tool pages.

• 2026-06-09
  • Added Sound Checker (version 0.1.2); allows teachers to confirm what sounds / graphemes are and are not in a word list or reading passage.
  • Updated the speed reader page. Fixed a few bugs; should work more correctly now.
  • Also, a few small updates to Blending Practice (version 0.11.4) and Word List Builder (version 0.12.5). Tweaked some color settings to ensure proper accessibility.
• 2026-06-08 More updates to Blending Practice (version 0.11.3) and Word List Builder (version 0.12.4). Fixed some bugs and added some features.



• 2026-06-05 Big updates to Blending Practice and Word List Builder. Fixed some bugs and added some features.
• 2026-06-02 (updated 2026-06-03 and 2026-06-04): Added Blending Practice and Word List Builder. Hopefully useful for teachers working with students struggling to learn to read.
• 2026-05-25: (updated 2026-05-27 with some tweaks): Added commandCraft — GUIs to help users create CLI commands for some powerful but complex programs: curl, ffmpeg, find, GPG, imageMagick, OpenSSL, password generators, rsync, tar, and xargs.
• 2026-04-01: Used Claude Code to create a Reading Modification Analyzer (aka a text modification checker) for teachers to check how modified a differentiated text really is. In my experience, LLMs do not do a good job of differentiating texts for English Learners. Ask for a 12th grade text to be differentiated down to a sixth grade level, and you might be lucky to get a 9th grade level. The Reading Modification Analyzer helps teachers see just how a reading differs from the original. It is at version 1.1, but I would very much appreciate feedback from teachers on how well it works for them.
• 2026-04-01: Updated the speed reader page.
• 2026-04-01 Updated the coin flip probability page.
• Claude Code and I made a Side-by-Side Reading Generator. Paste in the original and the modified versions and the page will create a document with them side by side, ready to print to paper or PDF. (Advanced users can download the document as an HTML file. Most teachers won't need that.)
• Updated 2026-01-30: Claude Code helped me expand and improve a Readability Checker I started working on a while back. Accepts plain text (just paste it in) and can import PDFs. Gives several readability scores, text information, and suggested English Learner supports.
• 2026-01-20: Vibe coded a speed reading page. Supports pasted text, .txt files and epub files. Created with the help of ChatGPT and Claude Code.
• 2026-02-21: Traditional Cryptography — interactive demos of seven classic pen-and-paper ciphers (Caesar, substitution, Playfair, Vigenère, rail fence, columnar transposition, and one-time pad), from trivially breakable to theoretically unbreakable.
• 2026-02-25: Early Modern Cryptanalysis — the birth of professional codebreaking: codebook history, the Zimmermann Telegram, Yardley's Black Chamber, and Friedman's statistical methods. Interactive codebook builder, Index of Coincidence calculator, and Kasiski examination.
• 2026-02-26: Cryptanalysis: Breaking Ciphers — the other side of the coin. Hands-on tools for breaking substitution, Vigenère, and transposition ciphers using frequency analysis, Kasiski examination, and column anagramming.
• 2025-01-21: Age Verification proof-of-concept. Still very rough, but the basics are there. Can you prove you are at least 21 by putting the pictures in order, quickly? If you can't it might be because you haven't been on Earth long enough. Only two topics so far. I'll add more as they are ready.
• 2025-01-06: Simplified Public-Private Key Pair Generation Demo — exactly what it sounds like. Shows the math behind creating public and private key pairs.
• 2025-01-04: Coin-Flip Probability Demo — have the computer flip any number of coins and keep track of heads and tails results.
• 2025-01-03: Simplified Diffie-Hellman key exchange demonstration — explains and sort of / kind of shows how two people can create a shared secret on an insecure channel using math.
• 2024-12-26: Fortune: a simple online version of the famous BSD Fortune program. (Now with more fortunes!)

You may also be interested in one of my other sites:

• ChrisSpackman.com: the site for my more professional documents and information.
• OsugiSakae.com: my personal and older stuff is here. May I suggest checking out "Mandated Reporter: My Conversations with Nnedi — a short story, set in the near future, dealing with GenAI agents in education.
• OpenHistory.org: my site for Free / Open content around Japanese History. I started it around 25 years ago, but have not updated it in a (very) long while. That will change soon, because I have switched back to LaTeX for it. (That just means I can update it more easily in the future, so I will.)
• Temporarily uploaded a gzipped tarball of The Encyclopedia of Japanese History, in case anyone is interested. I've recently had some success moving it back to LaTeX, so hope to resume development soon.