Day of Science joke

As today is the Day of Science, I thought a joke about science wouldn't go amiss... Here goes:

In a fifth-grade class, a teacher asked students various science questions, of which the following were the funniest:

Teacher: "What is the definition of a protein?'
Student: "A protein is something that is made up of mean old acids."

Teacher: "What kind of tails do opossums have?"
Student: "Reprehensible ones"

Teacher: "What is the spinal column?"
Student: "A long bunch of bones. The head sits on the top and you sit on the bottom."

Teacher: "How long does it take the Earth to rotate about its axis?"
Student: "The Earth makes a resolution once every 24 hours."
Teacher: "That's wishful thinking."