I am getting the error in step 8 of lightning experience specialist superbadge.

Challenge Not yet complete... here's what's wrong:  Please make sure you upload all of the Explorers from the spreadsheet. 
I tried folowing all the steps but couldn't find the exact solution.

Could anybody please assist here?

I am getting the error in step 8 of lightning experience specialist superbadge.

Challenge Not yet complete... here's what's wrong:  Please make sure you upload all of the Explorers from the spreadsheet. 
I tried folowing all the steps but couldn't find the exact solution.

Could anybody please assist here?

I have been able to get similar ones to work (based on prior challenges) but I am struggling here.  Probably a newbie mistake somewhere.  Any help would be appreciated!  Thanks, Aron

-> Page (Gives Error: Unknown property 'String.Id error)

<apex:page controller="NewCaseListController">
    <apex:form >
        <apex:pageBlock title="Case List" id="Case_list">
            <!-- Case_list -->
         <apex:repeat value="{!Case}" var="case">
            <apex:outputLink value="{!Case.Id}">{!Case.Id}</apex:outputLink>
            <apex:outputLink value="{!case.CaseNumber}">{!case.CaseNumber}</apex:outputLink>
        </apex:repeat>      
        </apex:pageBlock>
    </apex:form>
</apex:page>

-> Class

ublic class NewCaseListController {

    public String getCase() {
        return null;
    }


    public String getCases() {
        return null;
    }

private String sortOrder = 'CaseNumber';
public List<Case> getNewCases() {
    List<Case> results = Database.query(
        'SELECT Id, CaseNumber ' +
        'FROM Case ' +
        'WHERE Status = New ' +
        'ORDER BY ' + sortOrder + ' ASC ' +
    );
    return results;
    }
}