Sampling my class. There are 20 students in my class.

They sit in assigned seats, consisting of four rows of five students each. I want to take a simple random sample consisting of 4 of the students in my class. To do this I select a single student from each row as follows. I write the numbers 1 to 5 on identical slips of paper. I mix the slips in a hat and draw one at random. I count this number of seats in from the left in the first row and select the student in this seat. For example, if the number selected is 3, I select the third student in from the left in the first row. I replace the slip in the hat, again mix the slips, and draw a new number.

The student seated this many seats in from the left in the second row is selected. I repeat this process for the remaining two rows. Every student in the class has a 1-in-5 chance of being selected when I come to their row.

Thus, every student has the same chance of being selected. Is the sample a simple random sample? Explain.