PPT in PDF format to to introduce students to the two groups of stem changing verbs (o> ue and e> ie). There are numerous stem changers but I like to introduce them little by little to the Spanish 1 classes so they don't get overwhelmed. Students usually work with this set of verbs for an entire month or six weeks. Then I slowly introduce the other stem changers through out the year. It's important for them to have a strong foundation on these during their first year of Spanish so when they move onto upper levels they're truly prepared. I don't introduce them to the Preterit until Spanish 2.