Problem
Put the bat length in inches
Convert 3 ft 9 in to inches: 3 feet is 36 inches, plus 9 inches.
Using one unit (inches) lets us add and subtract lengths directly.
2.MD.A.1Analyze The UnitsFind Mia's covered length
Mia's 5 handspans are each 6 in, so multiply.
Repeated equal handspans add up to a total length.
2.MD.B.5Analyze The UnitsFind Liam's covered length
Since the two parts meet exactly with no overlap or gap, Liam covers the rest of the bat.
The whole minus Mia's part leaves exactly Liam's part.
2.MD.B.5Work BackwardsLiam's handspans cover 15 in — the whole bat minus the length Mia's handspans cover.
Why?
The two parts meet exactly with no gap and no overlap, so Mia's part and Liam's part together make up the whole 45 in bat.
Why?
If Mia's 30 in and Liam's part add up to 45 in, then taking Mia's 30 in away from 45 in gives back Liam's part, since subtracting undoes adding.
Find one of Liam's handspans
Liam's 15 in is 3 equal handspans, so divide.
Splitting his total evenly among 3 spans gives one span.
2.MD.B.5Work BackwardsTurn everything into inches, take away Mia's part, then share what's left into 3 — pure Grade 2 length sense!
- Put the bat length in inches
- Find Mia's covered length
- Find Liam's covered length
- Find one of Liam's handspans