24 fps
Animation happens at 24 frames per second (fps). Although video animation is done at 30 fps, 24 fps is the standard sound speed. 24 fps is the speed of film. With 24 fps you're dealing with filmmaking tradition, fractions and factors. 24 factors out to 1, 2, 3, 4, 6, 8, 12 and 24. 24 helps us divide into groups, into areas, into sections of time. If anyone in the class, teacher or student, can read music, they can build a connection right away with music. 4/4, 3/4, 2/4, 6/8 - these are all animation time signatures. Most animators animate with rhythm. The rhythm can come from a soundtrack, people speaking, or just a rhythm in their head. They all know where they are every 6 frames or so.
Pauses
Animation is not only a way to divide time and space, but that's what its structure is about: it refers to physics, math, music, cadence of language, poetry, even the shape, sound and texture of letters, consonants and vowels. The rhythm is in words, sentences and paragraphs. If you've got 24 frames, you can stretch that into 3 or 4 seconds of screen time using pauses. Pauses are your friends - they keep your animation from being constantly frenetic. Try to relate pauses to the real world. For example, kids know what it feels like to be on a swing set. At the top of each arc, there is about a 1/4 second pause. That might be a little long or a little short, but it's a good reference point. It is a 6 frame pause. We can call that a comma. If someone moving stops and changes direction, that's about a 1/2 second pause, or 12 frames. We call that a semicolon. If someone does a definite stop, before they do something else, that is a full second pause, 24 frames. Call that a period. It's not uncommon to see a full second pause in real life, but it is really hard for an animator to leave the character alone for a full 24 frames.
Real time vs. animation
You have to think in 2 time zones. If you blink your character and then 1/2 hour (in real time) later you blink them again, and 15 minutes later blink again, you may only have progressed 30 frames (in animation time), and you have a blink happy character. It's very distracting. You see this in newscasters when they have something in their eye.
How much to scoot before you shoot
Kids usually do scoot it and shoot it animation: move an object, click twice (called "shooting on twos"), and move again. My rule of thumb for spacing: hold out your thumb, grasp the tip with two fingers, that's about 1/4 inch, and that's worth 2 clicks. When you move an object, move it 1/4" by the rule of thumb. That way students aren't guessing, and aren't shoving things several inches at a time.
Anticipation
Anticipation gives you natural movement. Natural movement begins slowly, speeds up, and slows down again, unless arrested by a wall, a branch, or a predator. If you are starting from a standing position and moving to point B and stopping, you start with small increments: 1/32", then 1/16", 1/8", then 1/4" with 2 frames between each. Then maintain speed at a fat 1/4". At the slow down end, reverse the increments, so it isn't an abrupt stop.
Practical exercise
Give each student 24 frames: they have 1 second. They can animate unifix cubes, patterns in sand, a clay character, additive and subtractive graph paper, geometric shapes, moving something back and forth, rotating it, appearing/ disappearing. We can give them 3 criteria, and they have to animate 1 sec. They will probably ask how they can extend their second. One answer is by working together. Two students have 48 frames, 3 have 72, etc. Two or three kids working together works a lot better than four or five. Often times two or three work better than one.
Source:
http://www.animationtoolworks.com/
