Even without an instructor present to guide them, students can engage in scientist-like exploration using PhET. This is because PhET simulations are designed to help students explore cause-and-effect relationships and make sense of what they see. To accomplish this, simulations are designed to cue students to explore productively by using implicit guidance; i.e., the choice of controls, visual representations, and immediate feedback provided by visual changes as students explore [Paul et al. 2012, Podolefsky et al. 2012, Moore et al. 2013]. Thus, PhET is ideal for use in homework, and homework using PhET can use minimal directions, due to the implicit guidance in the sims. You can find example homework problems on the PhET website, under each simulation page, and on our Teaching Resources page.