After students know 4+4, I use Lots of 4s to teach 4+8, 8+4, 12-4, and 12-8.
First, have the students show three groups of 4. They know 4+4 is 8, and then by counting up with the last group of 4, they see that they have 12 total. They will need to recall these facts by remembering 4+4+4 = 12.( 4+8 or 8+4. )
Then, students can show that taking away one of the 4s, leaves them with 8, or taking away the 8, leaves them with 4.
12-4 = 8, 12-8 = 4.
Once students have learned the addition and subtraction facts with Lots of 4s, and they are ready for multiplication, show that three groups of 4, or 3 x 4, is the same as adding 4+4+4. Have the students manipulate those three groups of 4 into four groups of 3, to show that the answer is still 12. 3 x 4 = 12 and 4 x 3 =12.
