Reasoning · Grade 2-1 Ancient Numbers
Problem
The example 214 is 2 coils, 1 heel, 4 strokes — each symbol's count is that place's digit.
Seeing that 2-1-4 in the symbols matches the digits 2,1,4 is exactly the Grade 2 idea that the three digits of a number are hundreds, tens, and ones.
2.NBT.A.1Look For A Pattern31 has no hundreds and 3 tens, 1 one, so it needs 3 heels and 1 stroke.
Knowing 31 is 3 tens and 1 one is the basic two-digit place-value idea every second grader has.
1.NBT.B.2Make A Systematic ListSwap tens for heels and ones for strokes: heel heel heel stroke.
Listing the symbols one place at a time keeps the count exact and avoids miscounting.
1.NBT.B.2Make A Systematic List426 has 4 hundreds, 2 tens, 6 ones, so 4 coils, 2 heels, and 6 strokes.
Splitting 426 into 400 + 20 + 6 is the same place-value decomposition used to read any three-digit number.
2.NBT.A.1Make A Systematic ListSplitting 426 into 400 and 20 and 6 tells you how many of each symbol to draw.
The three pieces 400, 20 and 6 add back to 426 with nothing missing and nothing counted twice, so drawing all three pieces draws the whole number.
Each digit already names a count of one particular size of bundle, so the split into places is read straight off the numeral.
Draw each place as its symbol in turn: 4 coils, 2 heels, 6 strokes.
Drawing each place's symbols in order is just writing the number in expanded form with pictures instead of digits.
2.NBT.A.3Make A Systematic ListEgyptian numbers are just our hundreds-tens-ones in picture form: count one symbol per place and you can write any number you know!