LurnBot recommends this robot kit to age 9-12 yrs (Manufacturer: 8+ yrs)
STEAM Student Set from littleBits is a very nice electronics kit that will give your kids introduction into LED lighting, motors and the Internet of things. It is attractive, fairly well designed and a great learning device.
Kids can try out 8 fun challenges and find more from the app. Also, they can create their own invention.

Once you rent this robot kit, don't forget to download invention log file from manufacturer's site. Manufacturer (littleBits) suggests its own Invention Cycle which is a roadmap for kids' invention journey (Create - Play - Remix - Share). Though going through the invention cycle exactly in order is not mandatory, it can be a good way to start invention.
Since littleBits provides rich materials to fully utilize this robot kit, we recommend you to look over littleBits website first before kids start to create.

The STEAM Student Set engages kids in STEM/STEAM learning through creating fun inventions.
Supports learners in grades 3-8 with 19 Bits and 45 accessories, a 72-page Student Invention Guide with 8 challenges and 10 companion lessons, plus a 100+ page online Teacher’s Guide and Invention Logs.
Integrates Art & Design into traditional STEM learning.
Works for classroom/makerspace/home instruction or self-directed learning.
This robot kit sets you up for 16+ hours of step-by-step STEM/STEAM teaching and links to NGSS & Common Core.

19 bits: button, buzzer, 2 DC motors, fan, fork, inverter, light sensor, long led, number, power, pulse, rib led, servo, slide dimmer, temperature sensor, U power, 2 wires
45 accessories: batter + cable, 3 mechanical arms, 4 motorMates, 2 mounting boards, 2 screwdrivers, 4 screws, servo hub, servo mount, 24 shoes, USB power adapter + cable, 2 wheels

littleBits STEAM Student Set