Answer:
From largest to smallest they are: Universe, milky way, clusters, stars, planets.
Explanation:
Let's describe them from smallest to largest. In fact the size order is not exact as there are exceptions.
A planet is a nearly spherical body which is in orbit around the Sun. Planets are larger than moons.
A star is what planets orbit around. It is the source of light and heat. Our Sun is a star which is many times bigger than all of the planets.
A galaxy, such as our Milky Way Galaxy, is a collection of solar systems orbiting around a central core. Most galaxies have a supermassive black hole at their centers.
Galaxies also form clusters which are large scale structures.
The universe is everything. It contains billions of galaxies