Draw a number line with five lines, and label them "0," "1/4," "1/2," "3/4," and "1." For probability, a zero means that there is no chance of something happening. A one means it is an absolute certainty. Ask students to mark on the number line the probability of events like these:
A dragon will come to class in 15 minutes. (0)
You will be asleep in 12 hours. (1)
If I flip a coin it will land with tails showing. (1/2)
If I put four blocks in a bag, each with a different color, you will choose the green one. (1/4)
Have students experiment with a coin. They should flip the coin 20 times and mark down the instances of "heads" and "tails." While the results won't necessarily be 10 and 10, they will be close. Have students do it 20 more times. The more repetitions take place, the closer students should get to a true 50/50 split, showing the probability of a coin toss.
Ask students what the probability is of rolling a "3" with a six-sided die (the answer is 1/6). Then, if they are ready, add a second die to the situation. Now you have 12 different numerical outcomes, but many more different combinations (3 and 4, 2 and 5, and so on -- 36 all told). Ask students to figure out the likelihood of rolling a 2 (1 and 1) and the likelihood of rolling a 7 (many different combinations).