Units

emphasize the different counts of stuff: sheep, sticks, inches, tiles (area), ... point out that combining sheep counts with inch counts does not make a lot of sense

explore the idea of units as groupings: flock of sheep (could define an actual amount) so then 2 flocks of sheep and 3 sheep...

inches versus feet kind of thing

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Number as Matching
Pebbles of Various Sizes Digits
Carry Overs
Units Base Representations
Largest Number