Answer
$130^\circ$
Work Step by Step
1. There are $12$ hourly divisions on the clock face, each division equals to $\frac{360^\circ}{12}=30^\circ$
2. At 8:20, the smaller angle formed by the hands contains $4\frac{1}{3}=\frac{13}{3}$ divisions, thus the angle is $\alpha=\frac{13\times30^\circ}{3}=130^\circ$
