An entirely free 9th grade computer science curriculum from Carnegie Mellon University

“Think, Khan Academy on steroids.”

“This isn’t ‘drag and drop’ programming. We’re teaching [kids] to use Python, a text-based programming language that is the most widely taught language at the university level.” Professor David Kosbie

Currently, CMU’s CS Academy is running its second pilot program of its initial course offering, a 9th grade CS1, Intro to Programming and Computer Science. The course uses a custom graphics package written in Python to introduce students to the programming and problem solving skills required in Computer Science. It requires no prerequisite other than algebra readiness. The Program has 40 participating high schools across the United States and in Rwanda with over 1000 students using the curriculum.

Source: How we’re teaching K-12 students how to code – freeCodeCamp.org

Even if you’re not going to use all of the curriculum, the sandbox is very handy for working with Python.