Use your mouse pointer and the square to push the particles. Particles turn red when pushed. Change the movement speed (which is particle weight inverted - 0 = heavy and 100 = light). Press space to hide the movement speed.
Remember, I think that Scratch has a screen refresh ceiling, so you might need to move slower if the push block appears to teleport so then you can get the correct pushing effect. Feel free to remix to make it more accurate.
