The purpose of PowerPoint is to capture ideas and thoughts, not to present an entire paper or dissertation. These things are called bullet points not paragraph or sentence points. Writing full sentences loses the important data in the midst of extra words and information making it harder for people to pick out the key points.When you talk while people are trying to read at the same time, they will not hear you or they will not be able to read the information. People can not multitask well enough to capture both pieces of data especially when they don’t match.