  Astronomy observation is difficult in urban environments due to the
background noise generated by human activities. Consequently, promoting
astronomy in metropolitan areas is challenging. In this work, we propose a
low-cost, educational experiment called Wok the Hydrogen (WTH) that offers
opportunities for scientific observation in urban environments, specifically
the observation of the $21$ cm ($f_{21} = 1420.4$ MHz) emission from neutral
hydrogen in the Milky Way. We demonstrate how to construct a radio telescope
using kitchenware, along with additional electronic equipment that can be
easily purchased online. The total system cost is controlled within 150
dollars. We also outline the subsequent data analysis procedures for deriving
the recession velocity of galactic hydrogen from the raw data. The system was
tested on the campus of the Hong Kong University of Science and Technology,
which is located approximately 2 km northeast of the nearest residential area
with a population of 0.4 million and about 10 km east of the downtown area with
a population of 2 million. We show that a precision of $\Delta v \approx \pm
20$ km s$^{-1}$ can be achieved for determining the recession velocity of
neutral hydrogen with this relatively simple setup, and the precision can be
further improved with longer exposure time.
