Finally, you can shovel out the block which takes a very long time especially in hard snow. Some people insert two probe poles at the upper corners and use a parachute cord to saw out the block but that also takes quite a bit of time. But the best way is a snow saw mounted on the end of a ski pole. Next, simply step onto the block with your skis or snowboard and jump progressively harder until the block fails. Most people rank the test on a scale of one through seven.
Higher numbers imply stabler conditions.
In other words, when you jump on the block, you are testing the strength of both the slab and the weak-layer at the same time. In my opinion this can be a dangerous mistake because you are mixing apples and oranges. Slabs don't cause avalanches, weak-layers do, and that's what you should be testing. Certainly the stronger the slab, the more nearby anchors will help to hold the slab in place. But this has less and less effect with increasing distance to the anchor.