Circle Animation (condensed)
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Depth-value Notation (base 2)
    Counting and Reading
Boundary Calculation: Making Patterns Simple
Join and Take Apart Units and Boundaries
Addition: Sharing Space
Join Four Units; Join Five with Seven
Subtraction: Making Nothing
Take One from One; Two from One; Seven from Five
Multiplication: Unit Substitution
Three by Two; Five by Seven
Division: Finding Patterns
Twos in Six; Fives in Thirty-Five

boundary math
circle numbers

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∆ short animation
add/mult animation

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Boundary Integers as Circles (condensed version, 4 minutes)