But not all pollution is obvious. Sometimes, it remains hidden for us to uncover. A simple test scientists use to determine the acidity or alkalinity of a material is a pH test. In fourth grade, we are learning about how pH can show us if a change has occurred. For example, water that used to measure a pH of 7 may change into a pH of 12. This means something must have changed the pH of the water. Over the next couple weeks, we'll be looking at how one particular community must solve a mystery as to who polluted the community! We'll be testing water and soil samples...and that means we will be practicing safe science, too. Get those goggles on!