Candle, Candle Burning Bright

Most computers owned by schools are used in the Math department, a recent survey showed. Computer Science ranked second. The prime use for computers in any shool is drill and practice.

In drill and practice, the computer gives the student questions. If the questions are answered correctly, the student is rewarded. If the answer is wrong, the correct answer appears on the screen. Some educators frown on this, calling it "electronic flash cards." Others praise such programs, stating that they aid the teacher by reinforcing facts that children need to know.

Another type of educational software is the tutorial, where the computer "teaches" a particular lesson. Some tutorial programs make the computer an electronic page-turner; others allow the students to learn at their own pace, test the students, then review material or present new material based on the results of the test.

Some programs are advertised as educational games. They present learning as a fun experience. Some vendors will advertise a game as educational, if any single thing is learned. Arcade games are even called educational because they teach "hand-eye coordination." Maybe they do, but does this mean that they are truly an educational game?

There is another educational category -- simulation. This is one area where computers could be used to better advantage. There are very few good simulation programs available.

This program simulates a science experiment. A candle is drawn on the screen, and a jar is hovering above it. The program is very simple. To light the candle, press [SELECT]. To lower or raise the jar, press [START]. The candle cannot be lit if the jar has been lowered, but the jar can be lowered or raised whether or not the candle is lit. The white dots that move around on the screen represent the oxygen in the air.

This is a fairly standard experiment, and with a program like this, young children can learn about their environment safely. To light the candle, press [SELECT] and hold it down until the flame appears above the candle. The oxygen dots will move around on the screen. The flame on the candle will flicker because of the air movement.

Hold down the [SELECT] button until the jar starts to move. Once the jar is over the candle, the oxygen will begin to disappear. The oxygen still moves in the jar and the flame will flicker. When all the oxygen is used up, the flame will go out.

Hold down the [START] button until the jar starts to move up again. Notice that the oxygen dots will appear around the candle. If the jar is raised just before all the oxygen is used up, more oxygen dots will gather around the candle, and the flame will not go out.

This program uses the Player/Missile graphics for the jar, candle and the flame. Lines 50 and 60 contain the machine language to move the player (jar) up and down. Be sure that these lines are typed in exactly, or the program will not work correctly.

VARIABLES USED IN THIS PROGRAM

UP$	= machine language subroutine to move player up.
DOWN$	= machine language subroutine to mover player down
A	= free memory less 8K
PMBASE	= beginning of the memory for players and missiles
CANDLE	= memory location of where the candle will be drawn.
FLAME	= memory location of where the flame will be drawn.
TAR	= memory location of where the jar will be drawn.
C	= column where oxygen will be plotted.
R	= row where oxygen will be plotted.
0S(50,2)	= column and row of oxygen on screen.
0J(10,2)	= column and row of oxygen under jar.
FL	= state of flame (1 = flame lit, 0 = flame out).
JU	= state of jar (1 = jar down, 0 = jar up).
0X	= amount of oxygen visible.
F	= which of the three flames to draw.
B	= data being read.
X,Q,M	= dummy variables.

by Linda Schreiber

Listing: CANDLE.BAS Download