 Directionality and amount of broken glass. This activity will discuss the important elements to focus on when analyzing glass particles at a crime scene. The first thing you will notice is that particles start moving forward upon impact. Next, you will notice some particles moving backward. Looking at the overall distribution of particles, approximately two-thirds of the particles are going forward, and approximately one-third are going backward. Lastly, notice the quantity of glass that will fall to the surface. You have completed this activity. Directionality and amount of broken glass.