While in Google Sheets, select Tools > Create a new form. Select a template. You can choose from pre-existing templates like Event Registration and Contact Information. Otherwise, choose Blank form.

Jotform is a great way to collect data. In this tutorial, Jack Wallen shows you how to create your first form for easy data collection.

Learn how to create a fillable form in Google Docs. You can insert checkbox, signature box, etc. in Google Docs using this guide.