1) Clarifying 2) Demonstrative 3) Didactic 4) Didactical 5) Doctrinaire 6) Edifying 7) Educational 8) Educative 9) Elucidative 10) Enlightening 11) Explanatory 12) Expositive 13) Expository 14) Illustrative 15) Informative 16) Informatory 17) Interpretative 18) Interpretive 19) Learning 20) Ostensive 1) Clarifying 2) Descriptive 3) Didactic 4) Didactical 5) Doctrinaire 6) Educational 7) Educative 8) Elucidative 9) Enlightening 10) Explanatory 11) Expositive 12) Expository 13) How so 14) Informative 15) Informatory 16) Interpretative 17) Interpretive 18) Ostensive 19) Preachy 20) Preceptive 21) Warning 
indicating means whereby
• (a.) Conveying knowledge; serving to instruct or inform; as, experience furnishes very instructive lessons.
In·struct'ive adjective [ Confer French instructif .] Conveying knowledge; serving to instruct or inform; as, experience furnishes very instructive lessons. Addison. « In various talk the instructive hours they past.» Pope. -- 
[adj] - serving to instruct of enlighten or inform
adjective serving to instruct of enlighten or inform
serving to instruct or inform; conveying instruction, knowledge, or information; enlightening. · noting a case, as in Finnish, whose distinctive function is to indicate means by which.
serving to enlighten or inform