Think about an electronic device with a battery that you have to charge on a regular basis. 

1. What device is it?
2. When you are using the device, about how long does it take the battery to go from 100% charged to the percentage it has when you plug it in again to recharge?
3. About how long does it take to charge to 100% starting from 0% or nearly 0%?

4. Suppose you plugged in your device when the battery was 50% charged.

   How long do you think it would take to recharge the device to 100% compared to the time it would take if the device was at 0%? Would it be exactly half the time, more than half the time, or less than half the time it would take if starting from 0%?