Let your students talk.
They meet in a group of three and introduce themselves. In the group they start comparing each other: First person: "My name is ... I'm ... cm tall. What about you?" Second person: "I'm ... I'm ... cm tall. I'm taller than ... What about you?" Third person: "I'm ... I'm ...cm tall. I'm the tallest." Then they can go on with another topic or meet in a new group. The students sometimes have to use the phrase "as ... as" as well.
Besides comparing adjectives they practice numbers.