I get the feeling that when we say that electrons sometimes are particles or a wave depending on whether or not we measure it that what we mean by wave is not what first comes to people's mind. When we measure the electron it becomes a particle, if not then it is a wave. When I think of wave I think of something that goes up and down at a regular rate. Adding to my confusion is that I saw a documentary once where Susskind said how can particle be a wave and they showed a picture of a literal ocean wave. I think what is meant by wave is a probability cloud and the particle could be anywhere in that cloud once you decide to measure it. It just so happens that when you shoot electrons through a double slit that they appear on the other side in a pattern that looks like waves. To say that an electron is either a particle or a wave, I think wave is not the best use of English. I think a better formulation would be the electron in a definite location if you measure it, otherwise its being is spread out over space.