Assessment Tool

Lecture 3: Variables, Values, and Types

Content Tested: Writing a simple program

Lecture Content:

Variables
Declarations
Identifiers and Reserved Words
Types
Expressions
Assignment Statement
Variable Initialization

Goals:

Ability to synthesize and integrate information
Learn concepts and theories
Develop capacity to think for oneself
Develop ability to think creatively

Assessment Technique: Programming Activity

Purpose:

This planning and programming activity serves to emphasize the differences between the problem, algorithm, and programming stages of the programming process as well as encourage students to think about types of variables.

Activity:

We just saw a program to calculate a Celsius temperature given a Fahrenheit temperature. Your friend from England tells you that it is 30 degrees Celsius in her hometown today. Your friend tells you the temperature on a weekly basis, so you want to write a C program to do the conversion from Celsius to Fahrenheit. Before writing the code, remember the important parts of the programming process: Problem Description, The Algorithm, Writing the Code, and Testing the Code. Fill in the pieces below.

Problem Description: Define precisely what your program calculates, the input, and the output.

The Algorithm: This stage of the process requires you to think about how you'll solve the problem above (independent of a programming language). Recall that we used the following formula to calculate Celsius (C) from Fahrenheit (F): C = (5/9) (F - 32)

The Program: Write the program in C. We have provided the template for the program.

#include <stdio.h>

/* Comments:

*/
int main(void){

/* terminate the program */
return 0;
}

Possible C code:

#include <stdio.h>

/* This program prompts the user to enter a temperature in Celsius and reports the equivalent temperature in Fahrenheit
*/
int main(void){

double fahrenheit, celsius;

    /* prompt user for Celsius temperature */
    printf("Enter a Celsius temperature: ");
    scanf("%lf", &celsius);

/* convert celsius to fahrenheit */
fahrenheit = 32.0 + (9.0/5.0) * celsius;

/* print Fahrenheit temperature */
printf("That equals %f degrees Fahrenheit.", fahrenheit);

/* terminate the program */
return 0;
}

Possible mistakes:
Students might use %f instead of %lf in the scanf conversion code.
The calculation for fahrenheit might be wrong.

Possible Uses of Activity:

Have students work in groups to come up with the algorithm and then write the program as a class (since the students will have little experience with the syntax).
Break students into small groups (2-4 people) and have each group work on the activity. Encourage one or more groups to present their solution to the rest of the class (If groups write their code on transparency slides, showing the class the code is very easy since it eliminates the time for writing code on the blackboard or on a blank slide on the overhead projector.) If the instructor sees an error in the program, point it out and ask the rest of the class how one might fix the error and its type (syntax vs. semantic).