Small Matches is another way to prevent plagiarism and catch it, this is a step by step tutorial on how to use it:
On Turnitin Users have the ability to exclude small matches by either word count or by percentage. To exclude small matches within an Similarity Report click on the Filter and Settings icon below the sidebar.
The sidebar will load with the exclusion options. Below the Exclude matches that are less than: option enter into either the words or % fields the numerical value for small matches that will be excluded from this Similarity Report. To turn off excluding small matches click on the radio button next to Don’t exclude by size. To save the settings click on the Apply Changes button at the bottom of the sidebar. This feature can be adjusted at any time.
When a student closes an Similarity Report after using the exclude small matches option the Similarity Report will return to the assignment’s default setting for excluding small matches and the students changes will not be saved.