A teacher-submitted, NGSS-mindful lesson plan for using the PhET model "Forces and Motion - Basics". The model uses a tug-of-war with participants of different sizes and strengths, placed different distances from the center, in order to show how forces can combine in different ways to affect the motion of an object. The lesson itself includes a framing question, several investigations, and a request to back up a claim with evidence. NOTE: the web page given above is not itself the resource. The web page provides a link to a downloadable Microsoft Word document of the lesson plan, which is the resource.