The next figure illustrates the scale of the problem. The Gulf Stream image above has four kilometer resolution. In other words, each pixel is four kilometers on a side. This means you cannot resolve the shape of any feature smaller than four kilometers. Thus, a four kilometer resolution satellite image cannot show many small scale features that exist in the ocean.
Most satellite images have four kilometer or lower resolutions.
One kilometer resolution is considered 'good' resolution, but is more expensive to collect and process. The image resolution of satellite data is increasing as sensor technology and data processing techniques evolve. Someone in the class may notice that there are actually only eight different chlorophyll values in this exercise. You should expect each pixel to reveal a different chlorophyll value in real data. You will probably find that the students spend a lot of time agonizing over the accuracy of their calculations.