Random Blocks randomly select questions from a pool to be presented each time the test is taken. Unlike Question Sets, each random block can only be drawn from a single pool. You can only create random blocks from pools, not other tests.
NOTE: When you add questions to a test using the Random Block feature, each question
is linked from the original pool. Therefore, if you edit question within the pool, the revised version of the question will also appear in your test(s). However, after the test with the linked question is deployed, the questions will no longer reflect revisions made to the original.