It seems like your sentence was cut off, but I'll try to provide a helpful response based on what you've shared.

The statement "So long as teachers fail to distinguish between teaching..." suggests that there might be a comparison or differentiation that is important in the educational context. Often, discussions around this idea involve distinguishing between different methods, content, or skills in teaching.

For example, some common distinctions that are important in education include:

1. **Teaching Content vs. Teaching Skills**: Teachers need to differentiate between imparting factual knowledge (content) and developing students' abilities to think critically, solve problems, and communicate effectively (skills).

2. **Direct Instruction vs. Inquiry-Based Learning**: This involves recognizing when it's more effective to directly instruct students versus allowing them to explore and discover concepts on their own.

3. **Teaching for Memorization vs. Teaching for Understanding**: There's a difference between helping students memorize facts and fostering a deep understanding of concepts and principles.

4. **Formative Assessment vs. Summative Assessment**: Formative assessment is used during the learning process to guide instruction and improve student performance, while summative assessment evaluates student learning at the end of an instructional unit by comparing it against some standard or benchmark.

If you have a specific aspect or context in mind, feel free to provide more details, and I can offer a more tailored response!