The greater the charge, the farther apart the spread will be. So it would become electrically charged. The plastic cup is needed to assure that air currents do not disturb the sensitive foils. Test your hypothesis by placing a piece of paper between the charged balloon and the aluminum ball. In this activity, students bring charged objects near the aluminum ball and observe that the foil strips move apart.
Some electrons move from the ball down onto the foil strips.
With more negative than positive charges on the strips, the net charge on each strip is negative. Because like charges repel, the negatively charged strips repel one another. In a similar fashion, when a positively charged Plexiglas rod is brought near the aluminum ball, the electrons on the ball and the strips are attracted to the positive charges on the Plexiglas rod. This results in more positive charges than negative charges on the strips. The strips each have a net positive charge.