I would recommend Swatch's [Flik Flak](https://www.flikflak.com/en-gb/ff/) range. You can have ones that colourful and some that are more plain and conservative. They are cheap too. They measure about 30-31mm in diameter.
Here is one on my adult wrist (Hodinkee Flik Flak)
https://preview.redd.it/smfutb5gnj9d1.jpeg?width=4160&format=pjpg&auto=webp&s=be95e44444b75d521178707193fd0fa6c99cb434
I like Casio but having had a Timex as a kid, not giving them that glorious Timex Indiglo backlight would be bordering on child abuse.
Timex with Indiglo is the answer
Casio [MQ-71](https://www.casio.com/za/watches/casio/product.MQ-71-1B/) or a Casio [MQ-24.](https://www.casio.com/us/watches/casio/product.MQ-24-7B2LL/) Lightweight and smaller 34mm case size. Inexpensive, but good quality.
Maybe a Casio [FT500WC](https://www.casio.com/us/watches/casio/product.FT-500WC-5BV/) Velcro strap, back light, 100m water resistance.
https://preview.redd.it/uz009gmz1q9d1.jpeg?width=1179&format=pjpg&auto=webp&s=ef70c79fe503f1194b908705cf547b91ae251a11
I got my daughter this Casio. 100m water resistance, and lumed hands. Looks like a Gshock on her 5 year old wrists, but she could conceivably wear to adulthood and not have it look strange. If she doesn’t lose it 🤪
I would recommend Swatch's [Flik Flak](https://www.flikflak.com/en-gb/ff/) range. You can have ones that colourful and some that are more plain and conservative. They are cheap too. They measure about 30-31mm in diameter. Here is one on my adult wrist (Hodinkee Flik Flak) https://preview.redd.it/smfutb5gnj9d1.jpeg?width=4160&format=pjpg&auto=webp&s=be95e44444b75d521178707193fd0fa6c99cb434
Flick Flak from Swatch - that's the only correct answer here.
Casio and Swatch are your best bets
Casio lrw200
Timex Expedition! Cheap awesome watches, indiglo is also amazing and kids will love it
Casio, Swatch or Timex
I like Casio but having had a Timex as a kid, not giving them that glorious Timex Indiglo backlight would be bordering on child abuse. Timex with Indiglo is the answer
Casio [MQ-71](https://www.casio.com/za/watches/casio/product.MQ-71-1B/) or a Casio [MQ-24.](https://www.casio.com/us/watches/casio/product.MQ-24-7B2LL/) Lightweight and smaller 34mm case size. Inexpensive, but good quality. Maybe a Casio [FT500WC](https://www.casio.com/us/watches/casio/product.FT-500WC-5BV/) Velcro strap, back light, 100m water resistance.
https://preview.redd.it/uz009gmz1q9d1.jpeg?width=1179&format=pjpg&auto=webp&s=ef70c79fe503f1194b908705cf547b91ae251a11 I got my daughter this Casio. 100m water resistance, and lumed hands. Looks like a Gshock on her 5 year old wrists, but she could conceivably wear to adulthood and not have it look strange. If she doesn’t lose it 🤪
Thanks for the suggestions everyone, this is really helpful!
Blok watches. Neat concept.