Some students find it incredibly difficult to visualise nets being folded up into 3 dimensional shapes. The best way to gain confidence with this is having fun making lots of different shapes and I have already blogged about an excellent site for this where you can print off all sorts of nets and make some amazing shapes. With exams rapidly approaching you may not have time for that so here is a page from Nrich where you can watch 24 different nets being folded up to make 3d shapes. Before you press play each time try to work out what the shape will look like when it is folded, then see if you were right.
Here is a great site to discover all about three dimensional shapes. Find some scissors and glue, print off some of these nets and see what you can make! http://www.korthalsaltes.com/cuadros.php?type=p