Count Fixed-Interval Observation Opportunities — Free
A window includes an observation at its start when you use a start-inclusive schedule. Count sampling opportunities with that convention explicit, rather than losing the first observation in duration division.
The proof surface
Study timeboxes allocate work periods. This counts discrete observations on a fixed interval grid reset at the start of each window, not study blocks or recommended sampling frequency.
Why the flat version breaks
Omitting the starting observation
Duration divided by interval counts gaps, not all sample instants.
Always adding an end sample
An off-grid endpoint is not a scheduled observation.
Treating opportunities as data
A plan does not mean the observations were actually made.
How to work the transect tickstrip
Use minutes on a common elapsed-time axis. Each row starts a new interval grid; do not overlap windows if you intend to add their opportunities without duplicates.
Use a teacher-approved sampling schedule. The tool does not select a scientifically adequate frequency or infer how often an event occurs.
Floor the duration divided by the interval, then add one. A zero-to-thirty-minute window at seven-minute intervals gives observations at zero, seven, fourteen, twenty-one and twenty-eight.
Write the planned instants and distinguish a missed observation from a recorded zero. Endpoints are included only if exactly on the interval grid; no extra sample is forced at the end.
What the transect tickstrip replaces
| Question | Before | Visible working |
|---|---|---|
| Omitting the starting observation | Duration divided by interval counts gaps, not all sample instants. | Set the interval from the study plan |
| Always adding an end sample | An off-grid endpoint is not a scheduled observation. | Include the starting instant |
| Treating opportunities as data | A plan does not mean the observations were actually made. | Prepare the recording sheet |
A local arithmetic aid replaces hand calculation, not expert review. No paid AI service is needed.
Run it on the samples, right here
FIRST-LOAD
Input is processed locally and a draft is saved automatically in this browser profile when storage is available. Reset to sample clears that draft; Pro history has its own clear button. A state link encodes your inputs in its URL: share only non-sensitive rows. Browser history, clipboard and anyone receiving the link may retain it. Optional AI use below leaves this device; it is not required.
Schedule arithmetic only, not scientific study design. Check supervision, site permission and fieldwork safety separately.
Data note: Everything runs in this browser tab on the transect tickstrip: your observation window | start minute | end minute stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.
Go deeper: the companion app files the same reading as a index card with a stamped header
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the transect tickstrip reading, and holds your drafts on this device — one free run, then $ 4 one-time for the layer that keeps filing.
The transect tickstrip reading is complete for free. The optional $4 layer adds print, row CSV and the last five local reading summaries; it does not add hidden answers. Checkout is not configured yet; the article demo remains unlimited.
Open the count fixed-interval observation opportunities companionBoundary
Schedule arithmetic only, not scientific study design. Check supervision, site permission and fieldwork safety separately.
What this is built on
- Method: Floor the duration divided by the interval, then add one. A zero-to-thirty-minute window at seven-minute intervals gives observations at zero, seven, fourteen, twenty-one and twenty-eight.
- All sample records are invented examples. The app does not fetch measurements, policies, files or personal records.
- Google’s official pricing page, fetched 2026-09-27, lists free-tier access including AI Studio. Optional formatting only; limits and availability can change. Free-tier content may be used to improve products. Never paste private records there.
Before: Duration divided by interval counts gaps, not all sample instants. After: the transect tickstrip shows the working beside each named row so the reader can change the assumption and inspect the consequence.
Optional AI formatting, not calculation
For this transect tickstrip, use the free AI Studio interface only if available to you, with no paid API key. Manual entry completes the same workflow for free. Supply only fictional or non-sensitive notes. Review its output against the source; never paste unresolved questions into the numeric rows.
Format my non-sensitive notes for a transect tickstrip. Return plain rows only: observation window | start minute | end minute. Preserve supplied quantities exactly. Do not guess missing values; list questions separately. Do not calculate or add advice. I will check every row before pasting into the local tool.
Accepted schema: observation window | start minute | end minute. No AI response is executed as code.