Vote for GiveWell on the Project for Awesome website!: http://www.projectforawesome.com/
And more info about GiveWell, including how they do their assessments, is here: https://www.givewell.org/how-we-work/process
Many people have the view that charity is either ineffective or corrupt. In this video we discuss why it certainly doesn't have to be that way -if we take a more scientific approach to doing good. (Just to be clear though, this isn't meant to disparage other charities and/or Project for Awesome. I personally am a fan of Partners in Health (one of the main P4A charities) as well as many others that GiveWell doesn't currently list as it's top charities.)
(Ad revenue from this video will go to GiveWell, by the way)
If you enjoyed this video and want to know more, I really recommend Doing Good Better, by William Macaskill. I don't fully agree with every aspect of it (in particular, it takes a very utilitarian approach, even though you can take other moral views and come to similar conclusions). But it is a really excellent introduction to this topic, which is called Effective Altruism.
My account of Michael Kremer's work comes from Doing Good Better, but the original papers are below. Just to be clear though, this doesn't mean that textbooks, flipcharts and more teachers are never useful. Just that they were not in these specific places and times tested.
General overview: "Randomized Evaluations of Educational Programs in Developing Countries: Some Lessons" www.jstor.org/stable/3132208?
Textbooks: "Many Children Left Behind?
Textbooks and Test Scores in Kenya" www.povertyactionlab.org/evaluation/textbooks-and-test-scores-kenya
Flipcharts: "Retrospective vs. prospective analyses of school inputs: the case of flip charts in Kenya" www.poverty-action.org/study/flipcharts-and-school-inputs-kenya
Price of deworming tablets: www.evidenceaction.org/dewormtheworld/
The study I cited with the 108 health interventions:
Jamison, Dean, et al. (eds.). 2006. Disease Control Priorities in Developing Countries (second
edition) Oxford University Press
But the results are discussed in a paper available online (it's a good read!): https://www.cgdev.org/sites/default/files/1427016_file_moral_imperative_cost_effectiveness.pdf
FINALLY, if you've got this far, I think you'll really enjoy this: https://80000hours.org/