Invest in all three of what: Propher Muhammad (Peace be on him) described as the best Legacies you can leave behind Place of worship + Institute of Islamic Knowledge + Righteous children which in this case are products of the institute
Abu Qatadah reported: The Messenger of Allah, peace and blessings be upon him, said, “The best of what a man leaves being are three: a righteous child who supplicates for him, ongoing charity the reward of which reaches him, and knowledge that is acted upon after him.”
Source: Sunan Ibn Majah 237
Hazrat Jabir bin Abdullahra narrates that the Holy Prophetsa said:
“Whoever builds a mosque for the sake of Allah, like a sparrow’s nest for Allah or even smaller, Allah will build for him a house in Paradise.”
(Sunan Ibn Majah, Kitab al-Masajid wal Jumaah, Hadith 738)