Here's the deal: you want your students to practice addition and subtraction, and you'd like to do more than give them another cruddy worksheet, and you want EVERYONE to be challenged! You also want to be able to customize the activities so that each student gets the appropriate support and challenge, but you don't want to print ten different worksheets!
Here's what I came up with: give students problems where they have to add AND subtract in the same problem. Example: What are 2 numbers that are 3 apart and add up to 13? (Algebraically that would be X - Y = 3, and X + Y = 13, but you wouldn't do that with young children, okay?)
So how do your students solve this? Well, they can use the strategy "guess, check, adjust," which means they start with two numbers that add up to 13, say 10 and 3, and then check: are they 3 apart? No! They're 7 apart! So they have to adjust, but to adjust they use one of the properties of addition: "compensation." They take something from the 10 and give it to the 3 so that the numbers are closer together. Say they use 2, and now it's 8 and 5, which, wouldn't you know, add up to 13 and are 3 apart! Wow, wasn't that fun?
Okay, that's one part of it, but here's the REALLY COOL innovation: the problems have been formatted in a square grid, so that you can cut out problem strips in groups of 3, which your students can attach to the answer sheet. After they've completed a strip, you or a partner can check the answers, and then give them a second strip to complete - the strips have been sequenced so that they get trickier as you move across, or the same as you move down. Does a student need to be encouraged to do harder problems? Cut off a horizontal strip; need more practice with similar levels of challenge? Cut off a vertical strip.
There are also "warm up" and "ready, steady, go" problem strips, which introduce students to the concept of "apart & together."
I've included black & white as well as color versions of this activity as well as samples of students' work. There are over 45 different problems for students to work on and thousands of way to arrange the strip by using a pair of scissors!