In the past, I've taught integer addition with the 2-sided red and yellow chips, which worked well. The only problem with the chips was that they always ended up all over the floor! Then I discovered the Interactive Integers app -- so cool!! Students model the problem with the infinite supply of red and yellow chips. Then they make zero pairs by dragging a red and yellow chip together and "poof!" they disappear! The kids love it! When they cannot make any more zero pairs, they have their final answer! After they've practiced with this a few times, then I ask them to try to predict the sign of the final answer before making the zero pairs, and finally I ask them to predict what the final answer will be, not just the sign. When we are done practicing with the app, I explain to them that even if they don't have any chips or this app, they can still draw + and - signs on their paper and either cross out or erase zero pairs to get the final solution.
Next, we use the same app in the number line mode. Students must first set the starting point (the first number in the problem) by tapping the + or - sign to move right or left. Once it is set, it turns yellow. Then they use the + sign to move to the right if the second number is positive, or the - sign to move to the left if the second number is negative. After we are done with this portion of the app, I explain to them that they can use the number lines on their desks to do the same thing (or draw their own number line if there isn't one available). Most students preferred the number line method to the chips, but now at least they have 2 strategies to use for integer addition.