PowerPoint with stem-changing and irregular verbs introduced in chapter 1A from the Realidades 2 curriculum. Also includes practice with "decir" and "pensar." Approximately half of the slides have the verb provided, whereas the other half give two verb options from which the students need to choose. All slides have an animated text box so that the correct answer will pop up.
I like to use mini whiteboards with this conjugation practice, and to mix it up use the questions in a group competition. Only one student from each group answers at a time, and the first group to write the verb correctly gets a point. The board is then passed to another group member for the next question. To make it interesting you could also assign a special reward for every 5 questions a group gets right, such as shooting a ball into a trashcan or a mini basketball hoop. If the team makes the basket, they get an extra two points. Finally, I always post these PowerPoints on the class website to allow the students to use them to practice at home. Please feel free to do the same!