I dont know who you're teacher is, but i think he did a mistake..
The Format for a bank reconciliation statement show up like this:
                                                    $                $
Balance as per Bank statement                          xxxx
Add Amounts not yet credited                           
xxxx                                                                   xxxx
Less Cheaques not yet presented                      
xxxxBalance as per cashbook                                  
xxxxThats all.
About the errors:
I dont understand what do you mean about "the errors we find in updating the cashbook" can you explain more and Ill try to help you.
you look like a hard worker, we still have about 12 days for accounting and your working 

Note: xxxx means a random  number k?
hope I helped,
AL*Eagle