3rd Grade - Use Probability To Predict Future Events

Fractions and Probability
Use Probability to Predict Future Events
Use the results of probability experiments to predict future events (e.g., use a line plot to predict the temperature forecast for the next day).
Statistics, Data Analysis and Probability: use probability to predict future events The ability to understand trends and patterns to predict what might happen tomorrow or the next day based on those trends and patterns.

Sample Problems


Kelly rolled the die 6 times and she rolled a 6, 5, 3, two 4s, and a 2. Do you think the next roll should be a 1? (There’s no way to predict which side will come up. It is always a 1 in 6 chance.)


The television show, Wipeout, comes on at 3:00pm on Saturdays. I flip the channels at 3:20 and look for the show. I can’t find it. Why might it not be on? (It’s not Saturday)


I shot 100 baskets and made 25. What is the likelihood that if I practice every day in a month I will shoot 100 baskets and make more than 25? (Likely because the number of baskets may very well improve with practice.)


Nancy’s family likes to eat at the Chinese restaurant down the street twice a week. Nancy makes a note of what days of the week they eat at the restaurant and she notices that they eat there every Friday and Sunday. What prediction can you make for next week? Will they eat there again? (They will eat there on Friday and Sunday)


Write a little story that could explain why Nancy’s family eats at the Chinese restaurant on those particular days. What might change your prediction? (stories will vary)

Learning Tips


What future events in daily life can be accurately predicted by using past data? Ask your child for suggestions. Possibilities using old calendars (find them online) to predict what day Thanksgiving will fall on (always the 4th Thursday in November) or how many days are in April. (always 30)


Help your child to discern what events cannot be predicted at all. Examples might include highly unusual weather episodes for your area or what flavor gumball will first drop from the corner grocery’s machine that was just installed there and that you have not seen.


Talk with your child about the possibility of exceptions to what seems like a “definite” prediction. One example is the exception to the number of days in our year; it seems to be reliably predicted to be 365, but every 4th year there is an extra day. Can you think of other exceptions to standard predictions? Each family probably has routines that fit in this category; i.e., a family routine that is always in place except when there are houseguests and the children’s playroom is also the guest room.


Remind your child that predictions aren’t guarantees; that predictions are merely good guesses, based on data that you believe is reliable. Talk about times when your family’s predictions didn’t work out—a planned “snow day” when there was no snow that year, for example.


Children of this age often still rely on “magical thinking” which can be described by occasions when a child relies on flawed or unlikely predictions or occasions when a child believes him/herself to control an event which in fact he/she does not control. Examples would be the belief that “stepping on a crack” is the reason something unpleasant happened, or the belief that all bad things that happen in the family are the child’s fault, and conversely, that good things happened because the child secretly “wished” for them to happen. Help your child use his/her developing reasoning skills (the development of more mature reasoning skills is an important outcome of the study of probability and prediction) to separate out reasonable prediction from magical thinking.


Use online math sites for children (see the list below) to create interesting, and varied probability data so that children can have data to base predictions on in a fun and rapid way. Once a child has learned how to do such an experiment, one of these online data-collection sites can help a child compile up to a million experimental-data opportunities so that their predictions have a reliability that cannot be gained in a few pulls from a hat, spins of a spinner, etc.

Extra Help Problems


Jose still has the weather chart he made in kindergarten. It shows the weather for every day in the school year. He sees that on this date, when he was in kindergarten, it rained. Should Jose wear his raincoat today? Why or why not? (We don’t have enough information to predict; one day’s worth of data is not sufficient.)


Min’s family has been awakened in the middle of the night a lot recently. The cause seems to be the neighbor’s dog. Min decides to keep track of what nights the dog barks and he discovers that the dog has barked every Wednesday and Friday night. What prediction can you make for next week? (The dog will bark again those two nights, based on past performance.)


Write a little story that could explain why the dog only barks those particular days. Assuming the facts in your story are true, what could happen that would change your prediction? (Possibility: the dog’s owner works late those nights and the dog does not get brought inside and fed until very late at night. Many stories could be written that offer reasonable explanations.)


If it was 58 degrees at night and 70 degrees during the day, will it be likely or unlikely to be 95 degrees tomorrow during the day? (unlikely; unless a heat wave rolls into town)


If the spinner landed on square once and triangle twice in the last three spins, is it likely to land on circle in the next spin? (Show a spinner with ½ devoted to square, and ¼ to circle and ¼ to triangle.) (No, it is likely to land on square.)


You have gymnastics class on Mondays from 5:00 – 7:00 pm. Your mom drops you off at class at 5:00 on Monday. Is it likely you have class? What could happen that you wouldn’t have class (answers will vary; e.g., Monday holiday, coach is sick, you didn’t pay for the class)


You wake up at 7:00 nearly every day. Is it likely that you will wake up at 9:00am tomorrow? (No) Give some reasons why you might? (stayed up late the night before, have nowhere to go)


Dana’s baby sister cries every night around 7:00pm. The baby goes to bed about 8:30pm. Dana wonders if she’ll cry tonight when they’re about to eat dinner right before 7. What do you think? Why? (Yes, probably. The baby is perhaps hungry and wants to eat.)


Joe flipped a coin 25 times and it came up heads 10 of those times. Do you think it will come up heads again? (It’s a 50/50 chance. There’s no way to predict which side will come up)


The baseball team won the last three games. They are about to play the worst team in the league. Is it likely that they will win? (Yes, it’s likely, but never certain)


Record the temperature in your area for 7 days by making a line plot.


On the seventh day, predict the temperature for the next day. Write it down.


On the eighth day, record the temperature. Were you close to your prediction? Why or why no?


Look outside your window. Is it sunny, cloudy, rainy, or snowy? Write down what the weather is like for two days. Save your work to use in completing the next problem.


Predict the third day and record it when the third day comes. Were you right? Did you have enough days to make an accurate prediction?


Keep recording the weather for two weeks, but make a prediction the night before for each of the following days. Do your predictions become more accurate the longer you record the weather? Why or why not?


New neighbors moved into your neighborhood. You predict that they have children because you saw a few toys on their lawn. It turns out you were right because you see the children there the next day. What kinds of things do we use to make predictions? (our past experiences, things we notice that mean something to us, our understanding of the world)


You forget to take out the trash and your mom comes home. What do you predict will happen? (it depends; if your mom is the kind to expect the chores to be done, she might be mad. If she’s more easy-going, she might let it slide. Circumstances and personalities often make predictions difficult)


The television show, Josh and Drake, comes on at 5:00pm every night. When I turn the T.V. on to that channel at 5:15, will it be on? (Yes, if it is the scheduled night and there are no special circumstances)


The show isn’t on. What could have happened? (Maybe it’s not its regularly scheduled day—like it’s Saturday or Sunday or maybe something special has preempted the regularly scheduled program)


You have movie tickets for 7:20 and you arrive at 7:30. Describe why the movie has already started or why it hasn’t. (e.g. maybe the trailers are still showing or maybe not, maybe the projector was broken or some other problem with the theater)


You are playing the card game Go Fish. You have three sevens in your hand and there are only two cards left in the pool. Should you ask for a seven? (There’s a good chance it is in the other player’s hand)


The news anchor said there is a 60% chance of hurricane activity in our area. Should we evacuate? Why or why not?


My mother loves dessert. If I leave four bite size cupcakes on the kitchen table, how likely is it that they’ll be there tomorrow morning when I wake up? (Unlikely, you know your mom.)


My dad told me he would take me to shoot baskets at the park. What is the likelihood that he will take me today? If you answered that he would, why? If you answered that he wouldn’t, why?



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