For any two books (beginners/young):# 
or 
or 
# &# 
or 
or 
For history in general# or
For American History:# 
or or
(You can click most of those images and be taken to a place to either download the text and/or purchase it.)
A fourth that belongs in that top row is Basic Economics by Thomas Sowell. Conceived in Liberty is 4 volumes…so needless to say it’s long. But you can click the image for full PDFs and an audiobook for the whole text. Also be sure to check this artcle that speak on its contents.
I would also mention 33 Questions About American History You’re Not Supposed to Ask as a perfect book for high schoolers, and Crisis and Leviathan. Really everyone should read them, but 33 Questions is definitely better suited to the young student, and Crisis may be a bit much for some high schoolers…but it shouldn’t be.
Also check out:
History Reading List
I would also include I also agree that primary sources are great. They are often a tough read, but if you combine them with secondary and tertiary sources and assessments that comment on them and the period in which they were written, they can be invaluable.
there are also various lectures:
Thomas E. Woods: The Truth About American History (10)
The New Deal: History, Economics, and Law
The Economics of the New Deal and World War II
But at the very least have them watch the below lecture. It is the best, most concise yet comprehensive introduction to this world that I have ever seen. Sure there are plenty of books you will read and full lectures you will hear, and interviews you will see. But I know of no book that you could read in this amount of time that would offer a better intro to economics and history. Everyone should listen to it.