Thank you for your suggestions!
Our program serves as the "very first" step to inspire girls on STEM, which is to convince the girls that: CS is fun, not boring; CS is not rocket science, I can do it. Once they become interested and want to pursue more, there are other great, in-depth programs we will introduce them to, such as CodeDojo, Technovation Challenge, etc
As a result, our workshops are organized in a Fun and Easy setting, and the curriculum development focus on coverage (grade levels, categories, etc) instead of depth. In the example of Python, the girls will hear the buzz word of "Python" and get a first hand experience in two hours. After the workshop, they can move on to CodeDojo for Python 1,2,3 if they are interested to learn more.
Since we already offer patch workshops on Scratch, Python, etc, Raspberry Pi patch is a naturally extension for the girls to earn. The girls in the troop (like 5 girls) could share a Raspberry Pi in order to reduce the cost per girl to minimum (we don't want them spend too much money for 2 hours activity).