When you want to play games and relax, you should play games that will increase your skills of observation and give your eyes practice at rightly judging the distance and the shape of objects.
One student should draw a straight line on a wall [or board.] Let the others all stand at a distance of about 20 to 30 feet from the wall. These other ‘players' should then guess the length of that line by using a string, stick, piece of straw, etc., to find the right length. Then, when each one has settled on a length, return to the wall and measure your guess against the drawn line. The one who is most accurate is the winner.
In measuring distance: Take a spear or cane or pole and look into the distance to find a certain point. Then let each one estimate how many times the length of that chosen pole will go into that distance.
Also, let the students try to draw a line a certain length without a tape measure. On the ground or on paper, draw a line 6 inches long, or 12 inches long, and then measure to find out which student was closest in his estimation.
Such games give occasion to good practice for the eye, which is most important in painting.