1. Turn on the Size over Lifetime module.
It defaults to a curve type. If you click on it, you can see and adjust the curve in the Preview window, but if you
detach it to make it larger, it may not update as you make adjustments. This is where the Editor comes in handy.
You can keep it open and edit any of the regular parameters, because the entire component is also shown there.
2. At the top of the Particle System component, on the right, pick the Open Editor button.
3. Set the left/start value to 2.0.
4. Move the left key down to 1.0 and move the right/end key to 0.5.
5. Right-click over the curve at about .25 (25%) and Add Key, drag it up to 2.0.
This causes the particles to start small, then ramp up quickly, then shrink back down over time (Figure 11-24).