Assessment Tool

Lecture 16: Sorting

Content Tested: Selection Sort (and possibly other sorting strategies)

Lecture Content:

Sorting
Algorithms
Selection Sort
Efficiency Issues

Goals:

Learn concepts and theories
Develop capacity to think for oneself

Assessment Technique: Drama

Purpose:

To allow instructors to find out if students understand the selection sort algorithm and apply it to sorting people by height.

Activity:

We saw the selection sort algorithm in today's lecture. As a class we will sort ourselves based on height according to the selection sort algorithm. As a refresher, here's the code for selection sort with numbers in array b[].

void sel_sort (int b[], int n){
    int k, m;
    for (k=0; k < n-1; k = k+1){
        m = min_loc(b, k, n);
        swap(&b[k], &b[m]);
    }
}

int min_loc (int b[], int k, int n){
int j, pos;

    pos = k;
    for(j = k+1; j < n; j = j+1){
        if(b[j] < b[pos])
            pos = j;
    }
    return pos;
}

Line up randomly in one row as a class. If there are more than 20 people in the class then the instructor will ask for volunteers. Once you have found a spot in the line, we'll begin sorting ourselves by height according to the selection sort algorithm.

Note to Instructors

You probably do not need to give students a copy of this exercise. Instead, put the selection sort routine on the board or on the overhead projector so they have a reference. Encourage them to "sort themselves" with minimal help from you. Ensure that the students do follow the algorithm.

Possible Uses of Activity:

Extension: Use other sorting algorithms to sort people by height. These other algorithms include quicksort, merge sort, insertion sort, and bubble sort. If you do one or more sorting algorithms, be sure to explain the algorithm in pseudocode or real code (applied to an array) before starting. Students also like to see the algorithm on the board or on the overhead projector while doing the sorting activity.