Menimeter is a polling website that lets you create quick two question polls for your students (or other participants). You can select from a wide variety of question types including word clouds. Once a poll is created students use their phone or other device to answer the questions.
If you want to pay for the service, it will cost your $4.99 a month, but you get unlimited questions. There are other services like Mentimeter such as Poll Everywhere or Socrative, but I liked how easy it was to use Mentimeter.
This video will get you started - https://youtu.be/W9HNMve3_Ak