There are a few Presidents that did not have a Vice President.
John Tyler / 1841 - 1845 - no Vice President
Millard Fillmore / 1850 - 1853 - no Vice President
Andrew Johnson / 1865 - 1869 - no Vice President
Chester A. Arthur / 1881 - 1885 - no Vice President
There are Presidents that have gone their terms without a Vice President, but listed above are the ones that never had one.
This is true because imports get shipped and get sold in many places
I believe the answer is: Predict the outcomes of experiments before they are told the actual results.
By making them predicting the outcome of the experiment, dr. donelian would expose them with the fact that their prediction would often be wrong. After experiencing this, the students would no longer see the experiment as 'documenting the obvious'