PPT too often mimics the worst practices in education: a dominant "sage on the stage" with a passive group of students. This takes us to the heart of one of the real problems with PowerPoint: it was designed for presentations, not education. To be even more specific, PowerPoint with its bulleted lists and templates was designed as a means of making a sales pitch. If you are trying to sell a product or promote your company, you are probably not going to encourage a great deal of critical thinking. Instead, you are going to "push" your product and make it appear to be the logical and only choice. The last thing you want it to encourage your audience to think for themselves.
Edward Tufte is a widely-acknowledged expert in the field of the visual communication of information. Here are a few of his observations about PowerPoint:
“The pushy PowerPoint style imposes itself on the audience and tends to set up a dominance relationship between speaker and audience. Too often the speaker is making power points with hierarchical bullets to passive followers. The core ideas of teaching – explanation, reasoning, finding things out, questioning, content, evidence, credible authority not patronizing authoritarianism – are contrary to the cognitive style of PowerPoint.”
The conclusion is that the templates, bulleted lists, and style of PowerPoint is probably at odds with the real teaching and learning. In education, the purpose of a learning activity is meaningful learning, not simple memorization or the passive acceptance of information. Active or meaningful learning is basically summed up in Tufte's remark above: it is learning that engages in reasoning, questioning, and "finding things out." This is ultimately accomplished by the learner; the instructor and instructional activities simply facilitate the process.
The cognitive style of PowerPoint simply does not promote active, meaningful learning. It does promote passivity and shallow thinking. The practical application should be obvious: if you use PowerPoint in education, you are going to have to refuse to let PowerPoint dictate the form and content of your presentation. Rather, the purpose and content of your material should determine the form of your PowerPoint.