Hey @Gracie! Welcome to the forum!
That is normal. The servo that comes with the Quirkbot kit is not continuous.
Continous servos are a different type of motor. Here is an example of one https://www.sparkfun.com/products/10189.
If you are interested in using a continuos servo, you can buy them, off the shelf, in electronic shops (or hobby model shops). We will also start selling them soon on our online shop.
Hope this clarifies the confusion - don't hesitate to ask more questions!