Perhaps you should try some spelling variations:
"improving poor performance contract." » "improving poor performance contracts.", "improving sector performance contract.", "improving power performance contract.", "improving food performance contract.", "improving peer performance contract."
"improving pupil performance series." » "improving pupil performance studies.", "improving pupil performance size.", "improving social performance series.", "improving model performance series.", "improving judicial performance series.", "improving public performance series.", "improving civil performance series.", "improving audit performance series."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving pupil performance series.") or ("improving poor performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving pupil performance series.") OR ("improving poor performance contract."))*.
• Removing quotes may allow a broader search: (( improving pupil performance series. ) or ( improving poor performance contract. ))*.