Scratch

Well, a parabola is basically a trajectory of an object that is being accelerated, right? So one way to do it is to have variables called "X velocity" and "Y velocity", and in a forever loop move the sprite according to the velocities. In a separate script, simply continue decrementing the Y velocity by some constant.

Alternatively, use the equation: make the sprite always "set Y to" the square of its X position, for example.

or you could use trig...

this is how the first thing Hardmath123 suggested would look:

when [space v] key pressed
glide [1] secs to x: [-100] y: [-120]
set [x speed v] to [10]
set [y speed v] to [50]
set [gravity v] to [-5]
repeat [21]
   change x by (x speed)
   change y by(y speed)
   change [y speed v] by (gravity)
   end

you can do something similar by defining just a time variable and making X proportional to time and Y proportional to time * time:

when [space v] key pressed
glide [1] secs to x: [-100] y: [-120]
set [time v] to [-10]
repeat [20]
   change [time v] by [1]
   go to x: ([10] * (time)) y: ([180] - ([3] * ((time) * (time))))
   end

these are like animations of jumps.