Lets create a circuit that tests to see how different resistors affect the brightness of an LED. The voltage you should use is 9 volts, the red wire will be positive and the black wire is negative.
Set up your board similar to this, using the 4 resistors listed below and 4 LEDs of the same color.
Fill in the table
(order them 1-4)
What does increasing the resistance do to the voltage measurement of the LED?
What does increasing the resistance do to the brightness of the LED?