Sure! Here are the numbers 11 to 19 created using only the digits 2, 0, 2, and 5 once, with various mathematical operations:

11 = $5 + 2 + 2$
12 = $20 - 5 - 2$
13 = $20 - 2 - 5$
14 = $5 \times 2 + 2$
15 = $20 - 2$
16 = $20 - 5 - 2 + 2$
17 = $20 - 5 + 2$
18 = $5 \times 2 + 2 + 2$
19 = $20 - 2 + 2 - 5$

Let me know if you'd like any of the steps broken down further or need more clarifications!

Here are some questions related to the task:

1. How do concatenating digits help in generating larger numbers?
2. How does division work within these constraints to help form numbers?
3. Can you create the number 20 using the same digits and operations?
4. What are some common tricks for combining digits with operations efficiently?
5. How do the rules of operations (PEMDAS) affect the creation of these numbers?

Tip: When concatenating digits, you can create larger numbers that make it easier to reach your target, but be mindful of how operations influence the result!