What's in the bag?

This fall our first unit for the middle school algebra course I will be teaching will be on probability. I am also running a classroom of Chromebooks (two students to each device). I am guessing many of the students I have will already be comfortable with the basics of the probability unit I am required to teach so I want to promote thinking beyond what they have already learned with some open ended tasks.

I have had the privilege of learning from Terry Wyberg in past staff development and one of the activities he shared was 'What's in the bag?'. Each student or group of students is given a bag with 4 cubes placed in it of different colors. Students perform an experiment to try and determine the color composition of the bag without actually looking at more than 1 cube at a time (and replacing a drawn cube after looking at it).

I wanted to duplicate this activity with random combinations to be used on our computers. That way I don't have to create all these physical bags and kids will be able to look at patterns and develop their own ideas related to the number of trials and how they relate to the bag's composition. This will also be another program students (hopefully) could look at in creating their own programs as they move into javascript programming which I hope to be a parallel learning path within my algebra course.

Click here for a link to the web app and here for a link to the code.