A bus stop is a special place that you wait for a bus. The bus driver knows there will be people waiting at a bus stop and will watch out for you. Bus stops can just be a sign on a post, or a bench, or a proper shelter from the weather.
A caltrop is common name given to some (unrelated) plants that have seed heads with 4 or more sharp spikes, arranged so that one of them is always pointing upwards. The seed heads are very painful to step on. Metal devices of the same name and design can be thrown onto roads in front of cars to burst their tires.
A crop is a large amount of produce, like wheat or corn or any kind of plant grown for food. It is called a crop as you harvest it, as in a crop of apples.
You drop something when you let it fall down by itself. The students in the picture are dropping something out of a high window as an experiment. A drop is also a small globule of liquid, such as a raindrop.
Flip-flops are a kind of shoe that is made up of a sole that is held onto your foot by a strap that goes between your toes.
A gallop is the fastest gait of a horse. It has a beat of four, and all of the horse's feet are off the ground at once as it is galloping.
Hopping is a way of moving along on only one leg. You keep one leg up, and jump along on the other leg.
Scientific name: humulus lupulus
Hops is a plant grown for its flowers, which are added to beer to make it bitter. The hop plant is a climbing plant that is usually grown up poles or on strings in a field. Hop plants can grow very fast, and climb by wrapping themselves clockwise around anything they bump into. It grows vigorously in spring but dies back to a frost-hardy bulb in autumn.