Find Active Directory Schema Update History

$schema = Get-ADObject -SearchBase ((Get-ADRootDSE).schemaNamingContext) `
-SearchScope OneLevel -Filter * -Property objectClass, name, whenChanged,`
whenCreated | Select-Object objectClass, name, whenCreated, whenChanged, `
@{name=”event”;expression={($_.whenCreated).Date.ToShortDateString()}} | `
Sort-Object whenCreated

$schema | Format-Table objectClass, name, whenCreated, whenChanged `
-GroupBy event -AutoSize

$schema | Group-Object event | Format-Table Count, Name, Group –AutoSize