Answer: The median for the students is 2 and the median for the teachers is 3.
Step-by-step explanation:
Ordering the data for the students from the dot points:
0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4.
n = 20 which is positive so median position is average of: 
= (n / 2)                                     and                                = (n + 1) / 2
= 20 / 2                                                                           = 21 / 2
= 10                                                                                 = 10.5
2 is in position 10                                                         2 is in position 10.5
Average = (2 + 2) / 2 = 2
Student median is 2.
Teachers
0, 1, 1, 1, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 8
3 is in position 10 as well as in position 10.5.
= (3 + 3) / 2
= 3
Teacher median is 3. 
<em>(In attachment, teacher plot is first and then the student follows)</em>