@kcrippen and I used a cheaper version of the one that Dave had for some PD a few weeks ago. I think @dellingson had the Olloclip: https://www.olloclip.com Kent and I used these: http://www.amazon.com/Mpow-Clip-On-Supreme-Fisheye-Smartphones/dp/B00QXT58JA/ref=cm_cr_pr_product_top?ie=UTF8
They were great for the PD event. Teachers used it for the website iNaturalist and to look at Aurora fossil matrix that @vperez provided!