Grade 2 Math · Level 6, Enrichment + Grade-3 Prep
Parity Relationships
Predict whether a sum or difference will be odd or even without fully calculating it.
Questions like
- Is 5 + 7 odd or even?
- Is 37 + 45 odd or even?
How the lesson starts: Parity Relationships
Farmer Nell's duck pond
Quack quack! Farmer Nell's ducks love to swim in pairs. When two flocks meet, will every duck find a partner? We can tell without adding it all up!
The odd and even rules
4 ducks and 6 ducks are all in pairs, so 10 is even. 3 ducks and 5 ducks each have a lonely duck, but the two lonely ducks team up! 8 is even. 3 ducks and 4 ducks: one stays lonely. 7 is odd.
Is 5 + 7 odd or even?
5 ducks meet 7 ducks. 5 is odd. 7 is odd. Odd plus odd is even, because the two lonely ducks become partners! Check: 5 + 7 = 12. Even!