One great tool to help you with formative assessment is Peardeck. It is an online interactive presentation tool that features a variety of question types to get instant feedback from your students. It can be used for live presentations, center rotations or homework.
You can create decks from scratch or import content from Powerpoint, Google Slides, or pdfs. It's all saved in your Google Drive with unlimited space.
Be sure to also visit The Orchard for some great example decks at https://www.peardeck.com/orchard