In this lesson, we will undertake three distinct projects utilizing the DigitalRead feature of Arduino. First, we will explore the fundamental reasons why a push button is necessary when interacting with Arduino. Next, we'll learn to use a reed switch to detect magnetic fields. Finally, we will delve into the INPUT_PULLUP feature of Arduino, which eliminates the need for an external resistor with push buttons, and we will also examine the potential problems that arise if a resistor is not used in such circuits.