Learning in IXL

I have just learnt Geometric Sequences in a program called IXL. This is how I solve the equation.

 So if I had this equation, I would solve it like this.

1,    2,    4,    __,    16,    32

Multiply the four by the two.

4 × 2 = 8

To make the pattern complete, the number 8 must go in the blank space.