That means I have to conduct an experiment AND predict who will come to the party before I really know.

That could be a problem I need you to help me solve.  Do you remember the problem-solving steps?

Click here to review the steps for problem solving.

Yes. If your predictions were correct, this next step will help you learn another way to solve more difficult problems.

No. If not, that's probably because it's hard to make a  prediction when you don't know all of the facts.  It's also hard to predict without a plan. 

Let's use a picture, like a tree diagram to help us plan for solving the problem.

John used his tree diagram to show all of the possible outcomes or ways he can invite his two friends on this list. If Jamal and Minh are boys and Claire and Natasia are girls,  How many different pairs are there?

 
Type the number in the box and click the Check Me! button.
HINT: Repeating pairs are the same color, count them only once.

Let's see if you learned anything about how to use tree diagrams.
A tree diagram can help you
display possible combinations and outcomes.
predict events.
solve problems.
"see" a problem more clearly.
Click on the words tree diagram to check.