Am 10.01.2020 um 19:14 schrieb AMuzi:
https://bikerumor.com/2020/01/06/pat...don-wave-tech/

The answer was "Magnets" also in a FIRSTLegoLeague research by some 12
and 9-year old kids last weekend.
Their question was "How can I design a swing that my friend in a wheel
chair can operate on her own?".

Back on topic: my kids compared various routes in the city center with
Strava https://www.strava.com/athletes/rosapanther (how many people go
on the main road, how many take a parallel road on the right, how many
on the left? What's the delay of crossing the main road with pedestrian
traffic lights?).