Raspberry Pis in Makerboxes come preloaded with Raspian Operating System. You do not need to install an operating system
Quick Start Guide
Raspberrypi.org: downloads, community, help, forums, more
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Code.org
Learn Raspberry Pi with adafruit
Make: YouTube Channel
Program with Python - Introduction to Python Programming
Program with Scratch
Raspberry Pi Projects from Instructables
Raspberry Pi projects from Make: Magazine