The given ratio is
256 students : 8 buses
Divide each part of the ratio by 8 so that the "8 buses" turns into "1 bus"
256 students : 8 buses
256/8 students : 8/8 buses
32 students : 1 bus
The unit rate is 32 students per bus
Which is another way of saying each bus holds 32 students
This is similar to speed such as miles per hour. When we say something like 60 miles per hour, we mean "the car goes 60 miles in 1 hour". The key here is the unit 1, which is why I turned the "8 buses" into "1 bus".
