Teaching both of these concepts at the same time can have a beneficial affect as they complement each other well. One skill pushes the value up, the other pushes it down. I have seen many teachers get better results when introducing both concepts at the same time. Working on both of these skills makes a ton of sense. You can they interlock throughout just about every topic you will ever find. We start with the very basic facts and expand into word problems and situation based math. We also allow your students to get very creative with making their own sums and differences to create an end integer.
Pacing these skills towards mastery is the most difficult task for any teacher. Some students will get tripped up with one concept and others we just not get it. We find that remediating students that fall into the latter category is essential. This is where math facts flashcards come in very handy. Parents will often get involved when that is the case. Just send students home with flashcards and they should be good to go quickly. You will find worksheets that start with simple picture addition and subtraction. We then progress to basic math facts. From there we ask students to get creative and make their own advanced math facts. We offer a series of sheets that focus on the use of operators and we end off with solid real life word problem that feature sums and differences. Many teachers will prefer to focus on each skill individually and that is a matter of personal preference. If that is the case, this section can be used as a solid review for all your students.