Be sure to review your selection first for its mathematical accuracy and appropriateness for a school presentation.
https://www.youtube.com/channel/UCoxcjq-8xIDTYp3uz647V5A (Numberphile, excellent videos)
https://www.ted.com/playlists/189/math_talks_to_blow_your_mind TED playlist, so many more!
https://www.youtube.com/user/videomathtutor Video Math Tutor
https://www.youtube.com/user/Mathademics Mathademics
https://www.youtube.com/user/patrickJMT Patrick JMT free math videos
http://www.estimation180.com/ Daily estimation challenges to build number sense and problem solving skills
https://v1.expii.com/solve Math word problems
http://www.wouldyourathermath.com/ Choose your mathematical path and justify your choice
http://mathpickle.com/organized-by-grade/ Choose your math puzzle by grade or subject
https://player.fm/featured/math Playlist of many options
http://freakonomics.com/ Freakonomics radio. Podcasts about making economics and math relatable
https://www.quickanddirtytips.com/math-dude Math Dude podcast helping to make sense of math in your life
https://twitter.com/ddmeyer?lang=en Dan Meyer twitter feed
https://www.dailyinfographic.com/ New ones posted each day, lots of statistics and numbers on these (not all may be school appropriate)
http://www.adaproject.net/ Online book with problems
https://www.geogebra.org/ Online tools for graphing, 3D modeling, augmented realtiy and geometry
https://itunes.apple.com/us/app/photomath/id919087726 Photomath, snap a picture and get help solving the problem
https://sks.sirs.com/webapp/browse-issues?id=0 Business and economics stories from the SIRS Issue Researcher