Scratch is a computer language developed by MIT to allow kids to teach themselves how to code in a fun way. it’s designed for kids 8 and up, but there’s also a Scratch Jr designed for kids 5-7. He might try if he’s not ready for Scratch yet. I don’t know anything about the junior version, but my kids loved Scratch.
https://scratch.mit.edu/parents/
https://www.scratchjr.org/
Hoagies has links for enrichment for all ages and subjects.
https://www.hoagiesgifted.org/links.htm
Cyberchase (animated PBS show) is great for introducing math concepts (although recent seasons have shifted focus). Earlier seasons can be seen here:
https://pbskids.org/cyberchase/videos/?selectedID=...5c-0ec9-4490-9f88-7890cfb1689a
The National Library of Virtual Manipulatives has lots of ways to explore/play with math concepts:
http://nlvm.usu.edu/en/nav/vlibrary.html
I’ve always known cooking was great for math, but poster 08/04/2020 11:44 took it to a whole other level. I wish I’d read their post when my kids were still young.
https://www.dcurbanmom.com/jforum/posts/list/15/901600.page
Get him a tape measure and/or a timer. Let him go crazy measuring things and timing himself. He’d probably enjoy looking through the Guinness Book of World Records which you can check out from the library.
If he doesn’t know how to tell time yet, get him an analog watch. They make teaching models:
https://www.amazon.com/teaching-time-watches/s?k=teaching+time+watches
Games of all kinds have math components from counting spaces to keeping score. Some, like Sleeping Queens and Monopoly, have more direct math applications. Others, like Checkers and Othello haveconnections to geometry and higher math that I don’t really understand, but nonetheless acknowledge.
If he hasn’t learned money yet, I highly recommend it. I think it’s one of the very best math topics for young children because it lays a basic foundation across many areas to build upon.
I don’t know about his reading level but:
He might like Magic Squares. There’s an early reader that introduces the subject, but of course he can do magic squares without the story
https://www.amazon.com/Franklin-Magic-Squares-Step-Into-Reading-Step/dp/0375806210
The Sir Cumference picture books are great for introducing geometry concepts in a fun way.
https://www.amazon.com/kindle-dbs/entity/author/B00699FJ34?_encoding=UTF8&node=283155&offset=0&pageSize=12&searchAlias=stripbooks&sort=author-sidecar-rank&page=1&langFilter=default#formatSelectorHeader
Secret Codes:
The Mystery of King Karfu is a picture book mystery with a secret code to solve.
https://www.amazon.com/Mystery-Karfu-Casebook-Seymour-Sleuth/dp/0613084128/ref=sr_1_2?crid=1A66SKJS5ELHF&keywords=seymour+sleuth+cushman&qid=1652614197&s=books&sprefix=seymour+sleuth+cushman%2Cstripbooks%2C47&sr=1-2
For a more in-depth look at secret codes, The Third Grade detectives is a series of chapter books that uses them in their cases.
https://www.amazon.com/s?k=3rd+grade+detectives&i=stripbooks&crid=29831519WN50I&sprefix=3rd+grade+detectives%2Cstripbooks%2C37&ref=nb_sb_noss_1
My kids (grown now) enjoyed the Zoombinis and The Incredible Machine computer games. While I am sure those versions are outdated, there may be aps available now. In the case of The Incredible Machine, I think there would probably be copycat versions if nothing else.
Here are some summer festival we’ve enjoyed. While these aren’t specifically math oriented, they might be fun for your family as well. I don’t know how COVID will affect them this year. Also, look for the math festival which takes place in the Spring. (I haven’t participated in that one, but it looks great)
National Math Festival
https://www.nationalmathfestival.org/about-us/who-we-are
Montgomery County Heritage Days
https://www.heritagemontgomery.org/things-to-do/heritage-days/
Washington Folk Festival at Glen Echo
https://fsgw.org/washingtonfolkfestival
Artscape
http://www.artscape.org/
Maryland Renaissance Festival (be warned, Portapotties only)
https://rennfest.com/
Smithsonian Folklife Festival
https://festival.si.edu/