One thing that many people have trouble with when viewing the effectiveness of technology in the classroom, is that technology can not solve bad teaching. In many classrooms you will see techniques that are not effective but they are still being used, due to many reasons such as a lack of time to develop better methods or even a lack of energy by the teacher to get better. When technology is added to these situations, the technology by itself can not improve the learning going on in the classroom.
Technology acts like a multiplier where it can help make good teaching great but it can also help make bad teaching worse. If a person is using methods that do not focus on student learning but instead of a set instructional path, all technology will do is make this more efficient or give the teacher new ways to keep doing bad things. If a teacher is student centered and using formative assessment tools, project based learning or any other method that has shown to be very effective, then the technology can amplify the effectiveness of that classroom.
One key is to look at who is using the technology. If the teacher is the main person to use the technology in the classroom, there is little the technology can do to help the students learn more effectively. That becomes a prime example of a teacher-centered classroom. If the teacher is the focus of the classroom and the focus of the technology use, then the learning taking place will most likely not be improved by just using new tools.
If the students are the main ones using the technology, then there is a greater chance that the use of better tools or techniques can have a greater impact on student learning. But giving new tools to the students without having the proper environment for the learning to take place will not result in success either. There is a deep connection between the effectiveness of technology, and any other tool for that matter, and the environment of learning that is set up by the teachers and the students.