This wikipedia article has a double slit experiment with individual electrons which really shows the particle/wave duality.
What one should keep clear in one's head is that
a) the particle nature is given by the ability to locate a "particle" at a specific (x,y,z,t) maybe with some delta errors.
b) the wave nature is found in the probability distributions of these particles, the probability of finding them at a specific (x,y,z,t)
The following experiment is accumulating electrons one by one .
*successive accumulation of electrons *
In the first exposures one does not see much of a pattern. When enough statistics is accumulated the interference pattern is seen in the probability distribution for these electrons.
An experiment in 1987 first determined the "particle" position and the wave nature simultaneously.
In this recent experiment the slit the photon passed through is ingeniously known, and it shows that the photon passes from a unique slit.
That the interference pattern appears to be destroyed when the slit the "particle" passed through is known, is because the older measurements destroyed the information by disturbing the path when trying to detect it.
"Particle" in quotes because in the microcosm world the only concept of a particle is a disturbance in the experimental apparatus, that can be described as a billiard ball is described macroscopically, by its position . What we have is a quantum mechanical entity that has an (x,y,z) location within the uncertainty principle, which (x,y,z) is given by the quantum mechanical probability function describing the dynamics of its path. It is a probability wave , not a "mass" wave, i.e. it is a bad visualization that the "particle" is distributed in the whole possible space . Just the probability of finding the "particle" depends on a wave function distribution which creates an interference wave pattern at detection.