The effect of suspended solids on transparency and on the river was covered in the workbook. Suspended solids is the term given to the materials suspended in the water that actually cause the reduction in the transparency of the water.
Measurement of suspended solids is easy to understand. You simply filter a volume of water, then weigh the material left on the filter. It does require a very accurate balance (one able to weigh down to 0.0001grams), and for this reason you may not be able to do this measurement in your classroom.
The results, however, are easy to understand. The higher the value of suspended solids, the greater the problems in the river are likely to be. Transparency, on the other hand, has a complicated relationship to the amount and kind of sediment. Most students understand the relationship when both numbers increase at the same time. When one number (suspended solids) goes up and the other number (transparency) goes down, it may cause some confusion.