It's clearly often and falsely attributed to Einstein: https://skeptics.stackexchange.com/questions/8742/did-einstein-say-if-you-cant-explain-it-simply-you-don

It's clearly often and falsely attributed to Einstein: https://skeptics.stackexchange.com/questions/8742/did-einstein-say-if-you-cant-explain-it-simply-you-dont-understand-it-well-en https://skeptics.stackexchange.com/questions/8742/did-einste... https://www.google.com/search?q=%22If+you+can't+explain+it+simply%252C+you+don't+understand+it+well+enough.%22++Albert+Einstein https://www.google.com/search?q=%22If+you+can't+explain+it+s... (60k results)