Is there a doctrine that God grants revelation in layers? I've heard my school religion teachers say that God didn't reveal his true intent to humans all at once.


The Old Testament doesn't talk about heaven or hell.
The Trinity concept is not revealed in Old Testament--at least,
not prominently.
Polygamy and slavery are against God's will, but are not prohibited
in the Old Testament.


The idea is that humans were not yet ready to accept the greater truth, so God did not reveal the more correct idea.

Is this a standard Christian doctrine?

If so, what is its name? Gradual revelation?
Picking up on the comment by @curiousdannii, progressive revelation within the Bible itself is widely accepted among Christian denominations.

The Bible contains many indications of it, though most supporting passages quoted in Christian articles explaining the idea are found in the New Testament. See What Is Progressive Revelation? by Don Stewart for a solid presentation of the idea and its biblical basis from a fairly representative Christian perspective.

Progressive revelation beyond the Bible, called "continuous revelation," is more controversial among Christians, and is rejected by many mainstream Christian denominations. However, the LDS church believes that the Book of Mormon is a written revelation from God subsequent to the Bible, and some Christian groups, such as Quakers, Pentecostals, and Charismatics believe that God gives personal revelations to believers through the Holy Spirit.