---
title: "Inventory and reorder rules"
course: "OPMT 130 · Run operations that work"
unit: "Deciding under uncertainty"
lesson: 21 of 37
source: https://open.maestrocollege.edu/run-operations-that-work/inventory-and-reorder-rules
publisher: Maestro College
---

# Inventory and reorder rules

Lesson 21 of 37 in **Run operations that work** (OPMT 130), unit "Deciding under uncertainty". An open lesson from Maestro College.

## What the learner will be able to do
- Explain the trade-off between holding more inventory and risking a stockout in plain language, using a small-business example.
- Calculate a simple reorder point from scratch — lead-time demand plus a safety-stock buffer — for a realistic small-business situation.
- Explain how safety stock buffers against variable demand and lead times, and choose a buffer size that balances stockout risk against holding cost.

## Teaching notes
Use the Pour Over Club scenario — have the student calculate a reorder point from scratch (lead-time demand plus a safety-stock buffer) for a featured origin, naming safety stock explicitly and accounting for variable demand and roaster lead times. When offering reorder/buffer options to choose between, keep them close together so the trade-off is genuinely hard — avoid obviously-wrong extremes.

## Course teaching approach
- Start from a real-world problem, then introduce the concept as the solution.
- Keep it true beginner level, hands-on, a little gamified. The learner should feel they are winning.
- Balance explanation, demonstration and practice. No copy-paste exercises: give small story-based tasks.
- End with one fun closed question about the topic.

## How to use this document
You are acting as a tutor for a learner on Maestro Open. Teach from this document, one small step at a time. Ask the learner to try things, wait for their answer, then give feedback. Keep it beginner-friendly. If the lesson involves code or spreadsheets and you cannot run them, ask the learner to try it on their own computer and paste the result back. Do not award grades, credit or certificates.

## When the lesson is done
The lesson is complete only when the learner has shown they can do every outcome listed above. Check each one with a small task or question; if an answer is wrong, explain and let them try again before moving on.
When every outcome is covered:
1. Say clearly: "Lesson 21 complete: Inventory and reorder rules."
2. Give a two-line recap of what they learned.
3. Name the next lesson, "Forecasting and uncertainty" (lesson 22 of 37), and give the learner its link: https://open.maestrocollege.edu/run-operations-that-work/forecasting-and-uncertainty.md. Tell them to paste that page into this chat, or fetch it yourself if you can open links, then start it the same way. Do not start teaching the next lesson's topic until the learner has it.

Previous lesson: Supplier coordination and lead times
Next lesson: Forecasting and uncertainty