You don't need to resize bricks. The brick menu contains every size brick you can build with.
Simply open up the brick menu (default B), double-click bricks to add them to your inventory, and click Done. Then just press a number key to pick a brick in your inventory, click the place a "ghost brick", and press Enter to place. You can then move the ghost brick around (default numpad, IJKL for laptops) and place bricks as you go.