Choose Draw Prediction from the Analyze menu to be able to manually draw data on a graph. It can be used to predict the results of an experiment before you perform it and is a great way to test students' understanding of the experiment.
After choosing Draw Prediction, the cursor turns into a pencil. Click and hold down the mouse button and draw the prediction. Lift up from the mouse button to end the drawing. A new data set titled "Prediction" will be added to the data table.