I'd also concur with other posters providing a negative slant, and suggesting doing things other than hacking with modern computers or microcontrollers. There's

I'd also concur with other posters providing a negative slant, and suggesting doing things other than hacking with modern computers or microcontrollers. There's so many more fun things to do with a child. Chess, Lego, Meccano, Books, Art, Pottery, Music, woodwork/crafting, Modelling. That is to say, if you managed to get them able to understand and play chess first, and then go "how would we make a computer beat us at chess?" you'd have a better time than flashing LEDs or messing around with for loops and if/else (and unless your child is some sort of savant prodigy, getting a decent game of chess out of them is going to take a while...) Also if you want them to get into computing nowadays, I'd advise not doing any sort of smartphone use or social media yourself within sight of them. Children today haven't got that straight trajectory we did in the past from computers that presented a Basic prompt and really made you work for it, developing through the complexity and online nature they are now, where online and social is entangled and only ever a click away. My basic advice would be that they have their whole life to get into computing, and it's never been easier than it is now to learn and do, and there are loads more things to do that are exclusively things that can only be done with five year olds, and coding isn't one of them. P.s. one thing that I would suggest would be to take things apart - telephones (if they still exist) audio equipment, whatever you can find to take apart and put back together again, although again this idea was easier in the past when things had stuff in them other than just an smd microchip.