Developing student portfolios of evidence is not the end game, but rather a tool to demonstrate the mastery of learning. If developing a portfolio of evidence is just viewed as linking work, and checking off boxes that you "got it done", the students will miss the point. However portfolios that provide evidence of learning are powerful, but need to be approached intentionally.
The first thing that must be decided is about the evidence. What kinds of artifacts are to be represented and to what depth? If as a school system you are documenting work that represents mastery of your 5-8 cross-curricular transferable skills represented in your Graduate Expectations, the team needs to articulate how much evidence should be provided for each expectation. For example, if the graduate expectation is "that all students should use a variety of methods to express, receive, and respond to information and ideas", then the team needs to decide what evidence is sufficient to demonstrate that and articulate it. Will that include evidence of written work, videos of presentations or interviews, electronic survey methods and reflection papers? How many artifacts will ultimately be required to demonstrate mastery over a period of time? These are the kinds of questions the team must consider.
The actual tool schools will use will depend on their resources. Google sites, MAPS, Canvas, and Naviance are all options. Once you have decided what you want your site to demonstrate, you can move forward and design a tool. Most of my students create their world language portfolios in Google sites, however some like Bookmaker on the ipad and a handful are using Prezi sites. My requirements for their portfolio are that it can house documents and videos and that it is non-linear. Because the final site is summative, I am okay with the fact that there is no commenting function on google sites. My students house all their work in Google doc folders throughout the year and populate their portfolio as the year progresses. Their world language portfolio is an example of a class portfolio that has a range of assignments that have already been commented on, corrected and reflected . If you want to have the ability to comment directly on the portfolio of evidence, Google sites might not be the best choice. Once again, it is about deciding what your school's portfolio will measure and to what degree.