For this rough sketch, all you need is a pencil, an eraser, and a ruler.
a. Draw a Horizon line

b. Choose the position of the single vanishing point, which can be any position on the line.

c. Draw three squares, one above the horizontal line, one on the horizontal line, and one below the horizontal line. They can be of different sizes.

d. Using a ruler or any straight object, connect the sides of squares to the vanishing point as shown below.

e. To make the squares, cubes, draw lines parallel to lines of the square as shown below.

f. We can choose to erase the horizontal line and the lines that connect to the vanishing point. We will end up with the image shown below. We can see the bottom of the first cube and the top of the third cube.

Thank you, I gained a lot from this lesson.