The best simulations don't happen in isolation - there are activities beforehand and afterwards to ensure knowledge is understood, set expectations, model expert behaviour, and encourage reflection and integration of new learning. Here are some easy-to-use, free, web-based tools to enhance some pre- or post-sim activities.
These ideas and reviews of apps are courtesy of the Emerging Ed Tech blog - full story and more resources at http://www.emergingedtech.com/2015/10/free-technology-integration-tools-students-teachers-love/
Add questions on top of YouTube videos with EduCanon.
Add a private group discussion around a piece of digital content (like a video or website) with Tackk.
Build a short lesson around an online video (e.g. add supplementary content, a quiz, discussion, etc.) with ed.ted.com.
Quickly poll students in real-time or put together a full quiz with Socrative.