The most dependable way locate instrument references (and often instrument full text) in this database is to check the Availability field of the record for a Full Text from ERIC Available Online link.
The Availability field is located at the bottom of the record, immediately below the Publication Type field. Where available, click the ERIC full text link.
This will navigate you to an ERIC abstract record with pdf Download Full Text link in the upper right corner.
Click the Download Full Text link to open the document.
Scroll to the Methods section of the study and check for an 'instrument' section (nomenclature may vary but should normally be designated something like "Research Instrument," "Instrument," etc.).
Frequently instruments referenced in this database were designed specifically for the study in question and are not published. However, they often appear in the appendices at the conclusion of the articles/reports.