Is the following correct? In a high school basketball game, the first half ends with the possession arrow favoring black. Therefore, to start the second half, black throws the ball in. Once the throw in is completed, the possession arrow changes to white. Thanks!
This is correct. Once the ball is in-bounded the possession arrow switches.
See this website for more info about possession arrows if you are interested.
According to the 2014-2015 NFHS Basketball Rulebook (the latest I can find that was accessible - not accessible without purchase), this is known as "alternating-possession" as found in Rule 6, Section 4.
Article 1 states:
Other than the start of the game and each extra period, the teams will alternate taking the ball out of bounds for a throw-in.
Article 4 states:
The direction of the possession arrow is reversed immediately after an alternating possession throw-in ends
In your scenario, the possession arrow does change.