Open Middle®
Directions: Fill in the blanks with numbers that make the equation true.
4 + 5 = ___ – ___
Hint
If I cover the right side of the equation, what is 4 + 5 the same as? So, how much more do we need on the right side to make it the same as 4 + 5?
Answer
Many possibilities. As long as the difference is 9.
Some of the solutions are:
10-1,
Some of the solutions are:
10-1,
9-0,
12-3,
20-11
and so on…
Extension
How many different sets of numbers can go in there?
Source: Nanette Johnson
I don’t see how this is an “open middle” question. Wouldn’t it be more interesting to ask the child how many ways can we make this equation true (4+5= _ + _ )? What if we changed the “+” on the right to a “-” ? Then how many answers could we get? These questions could really get kids thinking.
Great suggestion. I made the change. Thank you for making the problem better.
I really liked the problem as it was for my 1st grade daughter- it let her develop a different understanding of the equal sign, and with a variety of examples tried she demonstrated her thinking in different ways which grew in sophistication.
10-1
no it does not
4+5=9-95=4