Day 04 Session Log

Date: 2026-03-23 Theme: My current project (S13) — pathfinding algorithm for mobility app Time: Evening session

Phase 0: SRS Review

21 items due (heavy day — Day 2 + Day 3 first reviews + Day 1 carry-overs).

SRS Score: 9/21 (9✓, 7△, 5✗)

Phase 1: Warm-up

Cold open — describe current project:

“I’ve been working on building a feature to find the fastest path from an entry gate to the exits.”

• Original: “creating a feature” → “building a feature”
• “a entry gate” → “an entry gate” (article before vowel)
• ✓ Good content

Interleaving (Day 3 — deepen understanding):

“I’m working on deepening my understanding of the pathfinding algorithm we’re using.” ✓

• “building” → “deepening” (corrected)

Phase 2: Grammar Drill — Project updates

Patterns: We’ve completed / We’re currently / The next step is / We’re planning to

Step 1: Transformation

“We completed the initial design phase last week. We’re currently building the backend logic, and the next step is to move on to the frontend.” ✓

Key correction:

• “We have completed… last week” ✗ — present perfect + specific past time = error
• Use simple past: “We completed… last week” ✓

Step 2: Fill in the blank

“We’re planning to release the first version by the end of the month.” ✓

Step 3: Production (actual project)

“We’ve completed the design phase. We’re currently building the pathfinding algorithm. The next step is to finish building the endpoint with an AI coding assistant.” ✓

Interleaving (managed to):

“I managed to add an authentication feature into our AI agent.” ✓ — perfect

Phase 3: Collocation Drill

Phase 4: Discussion Drill (Alex — London senior engineer)

Topic: Pathfinding project for mobility app

Key technical points discussed:

• Ride-matching service: find nearest taxi from user
• Chose Bellman-Ford over Dijkstra due to negative edges in path
• Correctness priority over performance (early stage product)
• Daily cron job for cache invalidation (road conditions rarely change)
• Biggest concern: scalability — Bellman-Ford O(VE) vs Dijkstra O(V log V)
• Future plan: migrate to Contraction Hierarchies (Uber’s approach)

Post-discussion corrections:

• Try: Road conditions don't change frequently. — not “a condition does not change”
• Try: We run a daily cron job to purge stale cache if anything changes. — “purge staled” → “purge stale”
• Try: Scale is my biggest concern. — lead with direct answer

💡 New collocations:

• purge the cache / invalidate the cache
• earn customers’ trust
• optimize for scale

Phase 5: Pronunciation

Target sentence:

“The reliability and scalability of the algorithm are our main concerns.”

Produced correctly. ✓

Phase 6: 5-sentence Writing + Score

Topic: My current project

User’s sentences (corrected):

1. Try: I've been building a shortest-path algorithm for my mobility project.
2. Good: We've completed the design phase. (needed article “the”)
3. Try: We're currently optimizing the algorithm. (“optimize” → “optimizing”)
4. Try: The next step is to migrate from Bellman-Ford to a simpler pathfinding algorithm that balances speed and correctness. (“is migrate” → “is to migrate”, “balance speeds” → “balances speed”)
5. Try: Our biggest concern is scale. (“was” → “is”)
6. Bonus: “You know Bellman-Ford is O(VE), which is slower than O(n log n) — we need to reconsider.” ✓ Strong technical reasoning.

Score:

Recurring Issues

1. “I” dropping — still occurring but less than before
2. Missing articles — “the design phase”, “an entry gate”, “the algorithm”
3. Present perfect + specific time — “We have completed… last week” ✗
4. -ing form after “are currently” — “We are currently optimize” → “optimizing”

Tonight’s Repeat Phrase

“The next step is to migrate from Bellman-Ford to an algorithm that balances speed and correctness.”

Say this aloud 3 times just before you sleep.