Yes, it is absolutely necessary for Christian parents to teach their children why Jews killed Jesus Christ when they are in kindergarten and elementary school. This teaching must be done using the Bible and with answer-question sessions with their children, guided by the Word of God, the Holy Bible, which is the final authority in the world.
The New Testament emphasizes the Gospel truth that Jews killed Jesus Christ and expects this truth to be remembered and taught by Christian parents to their children.
If Christian parents hide or suppress the Gospel Truth that Jews killed Jesus Christ, a Gospel truth that all four Gospels emphasize again and again, then God will punish their family and their children. God will make you, your children, and your family to taste a bit of Hell on earth as your punishment, if you refuse to teach proactively the essential Gospel truth that Jews killed Jesus Christ, as taught by the Holy Scriptures, proactively.
God requires (mandatory duty) all Christian parents to teach proactively and explicitly that Jews killed Jesus Christ as it is emphasized in the Word of God. It is necessary for Christian parents to submit to the Will of God.