Dear Zia,
As a matter of fact you will face more challenging studies as you step up the higher classes. Most of the children secure more than 90% in academics however they are not able to maintain such marvellous position unless they work harder, allocate more time to their studies, and try to solve the curricular problems on their own. So don't give up or lose your heart, "Failures are no more failures if they seem experiences to us".