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Bar Models: Mental Addition & Subtraction
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Foundational Skills
Read addition facts from bar model
\[ 3 + 7 = 10 \text{ and } 7 + 3 = 10 \]
Read both addition facts when all values visible.
Read subtraction facts from bar model
\[ 10 – 3 = 7 \text{ and } 10 – 7 = 3 \]
Read both subtraction facts from a complete bar model.
Identify whole from bar model
\[ \text{Whole} = 8 \]
Identify which number is the whole (total).
Identify parts from bar model
\[ \text{Parts: } 4 \text{ and } 5 \]
Identify which numbers are the parts.
Bonds to 10
Find missing part (bonds to 10)
\[ 10 = 6 + \square \]
Find the unknown part when the whole is 10.
Find missing whole (bonds to 10)
\[ \square = 4 + 6 \]
Find the unknown whole from two parts.
Bonds to 20
Find missing part (no bridging)
\[ 15 = 12 + \square \]
Find missing part without bridging 10.
Find missing part (bridging 10)
\[ 15 = 8 + \square \]
Find missing part when bridging through 10.
Find missing whole (bonds to 20)
\[ \square = 7 + 9 \]
Find the unknown whole (sum 11-20).
Two-digit + Single-digit (No Bridging)
Find missing part (subtraction)
\[ 47 = 43 + \square \]
Find missing single-digit part without bridging.
Find missing whole (addition)
\[ \square = 45 + 3 \]
Find missing whole without bridging.
Two-digit + Single-digit (With Bridging)
Find missing part (bridging)
\[ 52 = \square + 7 \]
Find missing two-digit part with bridging.
Find missing whole (bridging)
\[ \square = 45 + 7 \]
Find missing whole with bridging.
Two-digit + Two-digit (No Exchange)
Find missing part (no exchange)
\[ 59 = 34 + \square \]
Find missing two-digit part without exchange.
Find missing whole (no exchange)
\[ \square = 34 + 25 \]
Find missing whole without exchange.
Two-digit + Two-digit (With Exchange)
Find missing part (with exchange)
\[ 62 = 34 + \square \]
Find missing two-digit part with exchange.
Find missing whole (with exchange)
\[ \square = 34 + 28 \]
Find missing whole with exchange.
Complements to 100
Find complement to 100
\[ 100 = 63 + \square \]
Find what adds to a number to make 100.
Find whole (complements to 100)
\[ \square = 45 + 55 \]
Find the whole when parts sum to 100.
Crossing 100
Find missing part (crossing 100)
\[ 107 = 89 + \square \]
Find missing part when whole exceeds 100.
Find missing whole (crossing 100)
\[ \square = 87 + 18 \]
Find whole when parts sum to just over 100.
Three-digit (Multiples of 10)
Find missing part (multiples of 10)
\[ 590 = 340 + \square \]
Find missing part with three-digit multiples of 10.
Find missing whole (multiples of 10)
\[ \square = 340 + 250 \]
Find whole when adding multiples of 10.
Three-digit + Two-digit (No Exchange)
Find missing part (no exchange)
\[ 386 = 52 + \square \]
Find missing three-digit part without exchange.
Find missing whole (no exchange)
\[ \square = 52 + 334 \]
Find whole without exchange.
Three-digit + Two-digit (With Exchange)
Find missing part (with exchange)
\[ 372 = 45 + \square \]
Find missing part with exchange.
Find missing whole (with exchange)
\[ \square = 45 + 327 \]
Find whole with carrying.
Timer (Optional)
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