posted by cristina on .
I need help teaching my 2nd grader how to come up with the answer. Easy for an adult..difficult to explain to a child.
I am thinking of 2 numbers who sum is 15.
One of the numbers is 9 more than the other. Got the 12 plus 3 part. Help me explain it in its simplest terms
I'd use counters -- like M & Ms or pennies.
That is my thought but how do I pose the question? I took a deck of cards for counters and tried to figure out how to go about it.
THANK YOU by the way!
Put out 15 objects.
Then have your child take 9 of them away.
How many are left?
that's not the answer. its how to get her to 12 is 9 more than 3 that equals 15
start with your 15 objects
take 1 away, the pile left is 14 more than what she took away, and 14-1=13
take 2 away, the pile left is 13 more than what she took away, and 13-2=11
take 3 away, the pile left is 12 more than what she took away, and 12-3=9
ahhh, one is 3, the other is 12
x+y = 15
x-y = 9
2x = 24
x=12 , then y = 3