I found it hard to pinpoint a single K-12 school and their specific curriculum, but after much research I found that generally American's are taught that there were native American's that existed in the USA before the Europeans' and Asians' mass immigration process started.
It seems to be commonly taught that 'most came from Ireland and Germany, where devastating crop failures forced many residents to leave their homelands'.
Furthermore most settled in the city of New York 'where the population increased from 200,000 residents in 1830 to 515,000 in 1850. By 1860, New York was home to over one million residents. More than half of the city's population at that time were immigrants and their American-born children'.
For approximately 50 years before the First World War a lot of immigration was encouraged in order to boost the economy in the industries that required physical labour as immigrants were always willing to do any job.
What is evident is that Black slaves are not recognized as being immigrants to the US, it is just assumed that they were they due to previous shipping of slaves. Moreover the actuality that Natives existed before Europeans and other racial groups started moving into and occupying land in America is noted, but not hightlighted in the way that the European immigration occurrence generally is. For example, Eliis Island seems to be acknowledged frequently as opposed to the limited acknowledgement of the Natives, and the fact that (even though sparsely spread) they actually occupied the vast majority of the US lands prior to the immigrant invasion.