Sams minecraft facts

1. place a piston facing any direction
2. place a log of any type on the front of the piston facing the same direction of the piston
3. place a line of leaves 4 blocks long the same type as the log and 1 block away from the top of the log
4. place an observer facing the leaf block on the end of the line
5. place a redstone lamp on the back of the observer and turn on the piston

When the piston activates, the observer detects that the leaves are next to a log, and detects that the game now thinks that is a tree, and because it is a block update, it activates the observer, which flashes the lamp.

Level	Label	Ores	Notes
23
22
21
20
19
18
17
16
15
14
13	iron gold and redstone level
12
11
10
9	lava level
8
7
6	diamond level
5
4
3
2	bedrock level
1
0
-1