Click **Download** and follow the instructions to get your code onto your EV3 Brick. Press the ``center`` button on the EV3 Brick to run the program.
## Contemplate
On the road, when a driver sees and object, they slow their car down before coming to a full stop.
Program your EV3 Driving Base to do the same.
If the Ultrasonic Sensor:
* Detects an object less than `10` cm away, make the robot stop.
* Detects an object between `10` and `20` cm away, make the robot slow down.
* Does not detect any object, continue to move at full speed.
### ~hint
Consider using this block in your solution:
```block
if (true) {
}
```
### ~
### Sample Solution
```blocks
loops.forever(function () {
motors.largeBC.steer(0, 50)
if (sensors.ultrasonic4.distance() <10){
motors.stopAll()
} else if (sensors.ultrasonic4.distance() <20){
motors.largeBC.steer(0, 10)
}
})
```
### Download and test
Click **Download** and follow the instructions to get your code onto your EV3 Brick. Press the ``center`` button on the EV3 Brick to run the program.
## Continue
* Get together with other building teams and make a traffic jam by placing all of your robots in a line with varying amounts of space between them.
* Have everyone start their robots at the same time and see what happens.
* Refine your programs so that all of the robots continue driving at the same speed with equal distances between them.
* Click on the JavaScript tab and experiment with changing the values in the code.
* Add a custom image or sounds from the Brick or Music menus.
### Share
* Share what you think “efficiency in programming” means.
* Explore the different solutions other programmers came up with.
* Create a video of your project, especially your final presentation and your robot’s performance. Explain some important features of your software program.
