What would a lesson plan on the life of Jesus resemble in Public Education? According to my research, probably not much. Christian teachings in private school settings allow for faith based instruction. The subtle difference for public educators is that they would be limited to factual sources. This is a huge difference for learning.
The historical Jesus has 2 scholarly points that could be shared in Public Education. Most scholars agree Jesus was baptized by John the Baptist and he was crucified by Pontius Pilate. Factually, you can not stray from the facts. Teachers in public school most likely would be limited to the historical evidence of Jesus's existence that is neutral of Christian Bias.
There are some references teachers could reflect upon that are neutral. Outside of the Gospels, there is Greco-Roman references of Jesus that exist within a hundred years of his death. The works of 1st-century Roman historians Josephus and Tacitus. Josephus' Antiquities of the Jews, written around 93–94 AD, includes two references to the biblical Jesus Christ in Books 18 and 20. Roman historian Tacitus referred to Christus and his execution by Pontius Pilate in his Annals (written ca. AD 116), book 15, chapter 44. The very negative tone of Tacitus' comments on Christians make the passage extremely unlikely to have been forged by a Christian scribe  and the Tacitus reference is now widely accepted as an independent confirmation of Christ's crucifixion.
Does this make for a history lesson? Probably not in Public Instruction, which might explain the lack of Christian education in public schools.