Union
$$A \cup B =$$
{ air, earth, fire, memorization, note taking, reading, testing, time management, water }
Symmetric Difference
$$A \ominus B =$$
{ air, earth, fire, memorization, note taking, reading, testing, time management, water }
Difference
$$A - B =$$
{ memorization, note taking, reading, testing, time management }
Difference
$$B - A =$$
{ air, earth, fire, water }
Cartesian Product
$$A \times B =$$
{ (memorization, air),
(memorization, earth),
(memorization, fire),
(memorization, water),
(note taking, air),
(note taking, earth),
(note taking, fire),
(note taking, water),
(reading, air),
(reading, earth),
(reading, fire),
(reading, water),
(testing, air),
(testing, earth),
(testing, fire),
(testing, water),
(time management, air),
(time management, earth),
(time management, fire),
(time management, water) }
Classical element