Image Attributions

Wikimedia

https://commons.wikimedia.org/wiki/File:Simple_Feedback_02.png

ClipArtPanda

http://images.clipartpanda.com/cleanup-clipart-1250648204_2d8502c7f8.jpg

Netflix Canada

https://twitter.com/netflix_ca/status/541998181127421952

(fair use: use of their marketing material, published via social media, used in free, educational material, limited amount, with no foreseeable negative market effect for Netflix)

OpenClipArt

https://openclipart.org/detail/26221/Lightning_Icon-by-bpcomp

https://openclipart.org/detail/168575/safety-helmet-by-jonata

https://openclipart.org/detail/22539/rocket-icon-by-pitr

https://openclipart.org/detail/28689/no-sign-by-skotan

https://openclipart.org/detail/177571/dwcheckyes---complete-by-forest51690-177571