Allow & Deny Blocks are special Education Edition specific blocks that enable World Builders to create spaces where students can or cannot modify blocks. Allow Blocks permit the player to build or destroy, while Deny Blocks prevent these actions. These permissions do not affect using items such as doors, levers, or chests.
Allow and Deny Blocks work by affecting what happens above them, not below. As such, you can place them out of sight (such as underground) and they will affect the world above them. When using Allow and Deny Blocks together, the permission of whichever block is higher takes precedence. Placing an Allow block above a Deny block will prevent actions between the two blocks, but will allow the player to place or destroy blocks normally from the Allow Block upwards.
Using Allow and Deny blocks, you can easily preserve a specific location in an otherwise buildable world by placing Deny Blocks beneath the area you want to protect. Whereas in an Immutable World, you can place Allow Blocks beneath zones where you want students to dig, build, and create, all the while preserving the contents beyond those specified areas.
For example, an educator builds a world containing the Roman Coliseum. To protect the Coliseum, the world is set to immutable. However, the lesson calls for the students to enter the Coliseum and build a statue in the center of it. The educator places Allow Blocks under the area they want the students to build in, and now they can make their statue without risking damage to the rest of the world.
Updated August 16, 2017