1. Plan your download
Try fictional connections
Each preset uses a 600 MB file and 80% usable speed. These are invented teaching examples, not measurements or promises about any network.
2. Follow the units
The eight-times trap
A byte contains 8 bits. Capital B in MB means bytes; lowercase b in Mbps means bits. Convert megabytes to megabits before dividing by megabits per second.
Time (seconds) = MB × 8 ÷ (Mbps × usable percentage ÷ 100).
Here MB means 1,000,000 bytes and Mbps means 1,000,000 bits per second. MiB is a different unit and is not used in this lab. Displayed durations round up to a whole second.
3. Beat the departure clock
- You have five minutes before boarding. Try the station preset. Will the 600 MB file finish?
- Keep the file size fixed and double the speed. Predict what happens to the time, then test it.
- Set usable speed to 100%, then to 50%. Explain why the second download takes twice as long.
What this model leaves out
This is a constant-speed estimate, not a speed test. The usable percentage is your assumption: it represents the share of connection speed available to this download. Real transfers vary with shared connections, server limits, signal changes, protocol overhead and pauses. Doubling the speed only halves the time when the file size and usable percentage stay the same.
This activity does not download a test file, measure your network, store your answers or upload them.