I admit this example is more than bare-bones in that it has LEDs, but this lets me test it without needing a PC to show distance and check the accuracy of the sensor.
Step 1: Parts List
One (1) HC-SR04 Ultrasonic Sensor
One (1) Red LED
One (1) Green LED
Two (2) 560 ohm (Green, Blue, Brown, Gold) Resistors
Eight (8) Male/Male hookup wires
A ruler that measures centimeters (or use the serial monitor)