GPS-Paced Fartlek: Check Its Accuracy First

First, each group checks how far off their phone's GPS is on a measured 200-meter loop; then they run a fartlek alternating easy and fast paces with voice cues from the app. At the end they compare splits and decide when to trust GPS and when to trust a stopwatch.

How to play

1. Mark a 200-meter loop measured with a tape or the field lines; each group of four walks one lap with the app recording and compares the distance it shows (6 min).
2. With the teacher, each group sets its easy and fast paces in minutes per kilometer based on a previous test (3 min).
3. A 12-minute fartlek: 2 minutes easy and 1 minute fast; the group runs together and the app calls out the pace from the carrier's pocket, with a new carrier each block (12 min).
4. Check the splits in the app: were they steady, and did the GPS jump around on curves or near buildings (5 min).
5. Conclusions: what GPS is good for, when a stopwatch and cones are better and how big the margin of error is (4 min).

Rules

• The phone goes in a zippered pocket or an armband; no running with it in hand.
• Groups are formed by similar level so everyone can hold the pace.
• If someone can't hold the fast pace, they drop to easy without stopping.
• All groups run in the same direction.

Variations

Adaptations

• Wheelchair user: does the fartlek on a smooth loop with the same pace changes.
• Asthma: swaps the fast pace for a moderate one and keeps moving continuously.
• Visual impairment: runs with a guide and relies on the app's voice cues.

Learning goals

• Judge a GPS device's accuracy against a known distance.
• Control running pace in a fartlek workout.
• Use technology critically to plan running.

Equipment for a class of 25

• tablets or phones: 7
• cones: 8
• tape measure: 1

Teacher tip

GPS tends to be less accurate on short, curvy stretches, which makes the error very easy to see. Set the app to offline mode and check that voice cues can be heard with the phone in a pocket.

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