home / skills / cdeistopened / opened-vault / newsletter-subject-lines
This skill crafts ten plus OpenEd subject lines using proven formulas and a systematic evaluation to maximize opens.
npx playbooks add skill cdeistopened/opened-vault --skill newsletter-subject-linesReview the files below or copy the command above to add this skill to your agents.
---
name: newsletter-subject-lines
description: Write newsletter subject lines for OpenEd Daily using 15 proven formulas + 10 Commandments evaluation. Generate 10+ options, select best through systematic criteria.
---
# Newsletter Subject Lines
Write subject lines that get opens.
**Core Philosophy:** 80% of email performance comes from the subject line. Generate 10+ options, evaluate systematically, select best.
**Key constraint:** 35-50 characters ideal (mobile preview). Be clear even when truncated.
---
## The 3-Phase Workflow
### Phase 1: Identify Core Value
**What's the one thing that makes this newsletter worth opening?**
Ask:
- What's the most surprising insight?
- What problem does this solve?
- What will readers learn they didn't know?
- What would make someone forward this?
### Phase 2: Generate 10+ Options
Use multiple patterns below + formulas from `references/10-commandments-checklist.md`:
- Try 3-4 different patterns
- Apply sticky techniques from `references/sticky-sentence-techniques.md`
- Test with/without numbers
### Phase 3: Evaluate & Select
Apply evaluation from `references/newsletter-subject-lines-analyzed.md`:
- Score top 5-7 options with 10 Commandments (aim for 4-6)
- Use 4 U's test (Useful, Urgent, Unique, Ultra-specific)
- Final check: Would YOU open this? Would Sarah forward it?
---
## Core Patterns (With Examples)
### 1. Number + Why
Legitimizes with scale, creates curiosity about reasoning.
- "Why 1.5 million students are in microschools now"
- "83% of parents agree: schools aren't preparing kids for AI"
- "The $1,200 your ESA can actually cover"
### 2. Contrast / This vs That
Challenges assumptions with clear binary.
- "The gap that matters isn't algebra. It's initiative."
- "Small schools. Big difference."
- "Credentials vs Community: What actually helps kids thrive"
### 3. Contrarian Truth
Says what's obviously true but rarely said.
- "You don't need permission to start a school"
- "The other kind of testing (the one that actually works)"
- "What if school just... ended earlier?"
### 4. Curiosity Gap
Promises to reveal something specific.
- "What public schools don't want you to know"
- "The education trend public schools fear"
- "The real reason homeschool kids outperform"
### 5. Named Person + Insight
Borrowed authority from someone interesting.
- "Ken Danford quit teaching to prove schools are optional"
- "What Jason Skycak learned tutoring 10,000 hours"
- "She homeschools 5 kids and runs a business. Here's how."
### 6. Challenge + Data
Pattern interrupt backed by evidence.
- "Half of Prenda's guides have no credentials. Here's why it works."
- "Students who test themselves retain 80% more. Schools still don't do it."
- "4-day school weeks work. 900 districts prove it."
---
## Sticky Techniques (Use Sparingly)
Make phrases memorable and quotable.
**Contrast:** "Small schools. Big difference." | "To be everywhere is to be nowhere"
**Symmetry:** "Read for awareness. Write for understanding."
**Alliteration:** "Specificity is the secret" | "Practice produces permanence"
**Rhythm:** Two short parallel phrases that feel balanced
---
## OpenEd Swipe File
Real subject lines that performed well:
| Subject Line | Pattern |
|--------------|---------|
| "Why 1.5 million students are in microschools now" | Number + Why |
| "The gap that matters isn't algebra. It's initiative." | Contrast |
| "Small schools. Big difference." | Sticky (Contrast + Rhythm) |
| "You don't need permission to start a school" | Contrarian Truth |
| "What testing actually works (it's not SATs)" | Curiosity Gap |
| "The getting by trap" | Label (names phenomenon) |
| "83% of parents agree" | Number + Validation |
| "Credentials vs Community" | This vs That |
---
## Workflow
1. **Identify the core insight** - What's the one thing that makes this newsletter worth opening?
2. **Match to pattern** - Which pattern above fits this insight?
3. **Generate 10+ options** - Try 3-4 different patterns
4. **Select best** - Would YOU open this? Would Sarah forward it?
---
## Preview Text Formula
Complement subject line, don't repeat it.
`[Specific claim]. [Context]. [Gap/tension]. PLUS: [bonus]`
**Example:**
- Subject: "Why 1.5 million students are in microschools now"
- Preview: "It started with frustrated parents. Then the pandemic hit. Now it's a movement. PLUS: how to find one near you."
---
## Anti-Patterns
**Don't:**
- Start with "This week in..." or "Our latest..."
- Use clickbait you can't deliver on
- Write vague promises ("Something exciting")
- Use ALL CAPS for emphasis
- Add emojis
- Stop at 2-3 options (generate 10+)
- Use hedge words ("might," "could," "possibly")
- Write generic promises ("many people" vs "1.5 million students")
---
## 10 Commandments Quick Reference
Score your top 5-7 options. Aim for 4-6 per subject line:
1. **Numbers** - Specific stats, not "many" or "several"
2. **Negativity Bias** - Potential loss, mistake, consequence
3. **Pattern Interrupt** - Challenge common belief
4. **Target Callout** - Name specific audience
5. **Problem Callout** - Identify pain point immediately
6. **Confidence** - Strong language, no hedge words
7. **Aesthetics** - Clean, scannable, under 50 chars
8. **Benefit** - Clear outcome promised
9. **Social Proof** - Authority, results, validation
10. **Warning** - Urgency or importance
**Full framework:** `references/10-commandments-checklist.md`
---
## Quality Checklist
Before finalizing:
- [ ] **Under 50 characters?** (mobile preview test)
- [ ] **4 U's pass?** (3/4 minimum: Useful, Urgent, Unique, Ultra-specific)
- [ ] **Would you remember it 5 minutes later?** (memory test)
- [ ] **Would you forward it?** (quotability test)
- [ ] **Is meaning clear even truncated?** (clarity test)
---
## Bundled Resources
| Resource | Contents |
|----------|----------|
| `references/newsletter-subject-lines-analyzed.md` | Real OpenEd examples with full scoring |
| `references/10-commandments-checklist.md` | Evaluation framework with examples |
| `references/sticky-sentence-techniques.md` | Literary devices for memorable lines |
---
## Related
- `opened-daily-newsletter-writer` - Full newsletter workflow
- `article-titles` - Blog/article titles (longer, SEO-focused)
- `segment-titles` - Segment headline writing
---
*Generate 10+ options using multiple patterns. Score with 10 Commandments. Select best.*
This skill writes high-open-rate subject lines for OpenEd Daily using 15 proven formulas plus a 10-Commandments evaluation. It generates 10+ distinct options, scores the top contenders with systematic criteria, and selects the best lines optimized for mobile previews. The goal is clear: increase opens with concise, memorable, and honest subject lines.
I identify the single core value or insight in the newsletter, match that insight to multiple subject-line patterns (Number + Why, Contrast, Curiosity Gap, Contrarian Truth, etc.), and produce 10+ candidate lines across 3–4 patterns. Then I score the top 5–7 options using the 10 Commandments and the 4 U's test (Useful, Urgent, Unique, Ultra-specific) and run final checks for length, clarity when truncated, and forwardability.
How many subject line options will you produce?
I generate 10+ distinct options and then shortlist the top 5–7 for scoring.
How do you pick the final subject line?
I score shortlisted lines with the 10 Commandments, apply the 4 U's test, check mobile length and clarity when truncated, and choose the line that best balances score and real-world appeal.