Blocking is essentially the skeleton of the body!
© George Toombes
Blocking is a very important second step of the animation (right after creating the reference). It helps to see what are the key poses, how the story is going to be told and to better understand timing between the main poses. In general, it helps to see how the animation is going to develop further.
George also shared with us a very useful video on how to approach blocking:

Here is my first attempt on blocking:
Animated Artefact
For my artefact I decided to develop an idea I had last term – a story about a firefly. I have already created a previs:
The next step is to put a character into the scenes and animate it.
The character that Im going to use is a model ‘Artemis’ by Ramon Arango:
