You can confront atheism in the classroom!  You can.  "Easier said than done," you may say, but I assure you that it can be done.  How?  Follow these three suggestions:  Pray, practice, and provide.
    When you are in a classroom situation and the subject of atheism, or evolution, comes up, just take a few minutes to pray.  It doesn't have to be a long prayer, and it doesn't have to be said aloud, but it should be said and it should be a petition to God to grant you the faith or strength needed to withstand the pressures placed upon you by the teacher or your fellow students (Luke 18:1; James 1:5; Psalm 55:17).
    Your prayer will do no good if you are not living the way that you should (Proverbs 15:8; James 5:16), so you must practice your religion.  That is, you must live like a Christian.  You must act like a Christian.  You must talk like a Christian.  If you do these things, not only will you confront atheism in the classroom, but you will also strengthen others who know what the Bible teaches.  Remember Matthew 5:13-16?  Our influence, or example, or light should mean a great deal to us for on the judgment day we will be held accountable for how we have lived before others.
    Finally, you need to provide.  Provide what?  Provide answers for the questions that your friends may have about God, the church, salvation, or any thing that is right (I Peter 3:15; Philippians 1:17).  When we are in a situation where the truth is being ridiculed, we need to pray as Daniel did, and to stand, and advance as David did.  When a Christian can explain to others why he believes what he believes, then they will at the very least respect him for it.
    It takes sincerity, determination, study, and dedication, but I assure you that you can confront atheism in the classroom, and that you can win others to Christ in doing so.