The Pimoron Unicorn Hat is a very nice 8×8 matrix that can produce a really bright display.
ScratchGPIO has several commands so that it can be controlled using Scratch.
To use it with ScratchGPIO, please install the software from Pimoroni
You will need your Pi to be connected to the internet and then launch an LX Terminal session and type
\curl -sS get.pimoroni.com/unicornhat | bash
To use it – please follow the examples on the left