- This app is made to teach children how traffic lights works. ★ ★ ★ ★ ★ FEATURES ★ ★ ★ ★ ★ - Has two modes: Auto and Manually. Auto mode uses a countdown timer that starts out with a green light, then turns yellow, then turns red. Manually mode stops the timer and you can change the lights with a tap on the screen. - Display time of each light is configurable. - Support multiple devices and screen sizes.