Click on a function below.[br]Look for the sections of the function that have positive, negative, zero, and undefined slope.[br]Drag the point on the function (in blue) around and watch what happens to the black point.[br]Does it do what you expected?[br]When you want to try a new function, you can erase the traces by clicking the arrows in a circle on the top right corner of the graph. Then uncheck the function you have and try the next one.