Use concrete materials or fingers to model and solve simple addition and subtraction problems

1. Red Blocks 4 - 1
2. Red Blocks 1 - 1
3. Red Blocks 2 - 1
4. Red Blocks 3 - 1
5. Red Blocks 5 - 1
6. Red Blocks 6 - 1
7. Red Blocks 7 - 1
8. Red Blocks 8 - 1
9. Red Blocks 9 - 1