First, make a guess to approximate the value of the height of a penny, a school and the Mount Everest.
Penny:
Since a penny it is thick enough not to break but thin enough to fit in yout pocket, let's assume that its width it's about 1 mm.
School:
A human being's height it's usually between 1m and 2m. A small tower can have a height of 100m. If your school has a couple of floors and a typical human can perfectly fit on them, a nice guess would be to assume that the height of your school building is about 10m.
Mount Everest:
The Mount Everest is the tallest mountain in our planet, measured from the sea level. It's altitude is about 8.85 km.
Next, calculate how tall would a million pennies tower be.
Since each penny has a height of 1mm, the tower would have a height of:
1,000,000 mm. This is equal to 1,000 m or 1km.
Therefore, a tower of a million pennies would be certainly taller than your school building but not taller than the Mount Everest.