I use this activity as an assessment after we have covered the structure and function of DNA. They can use the book as a guide but I tell them that they should do a dry fit before gluing any pieces down to make sure that the DNA Ladder fits on the paper. I have them attach the ladder to the back of the worksheet. There are also questions to answer on the structure and function of the DNA molecule. This activity supports Grade Seven California State Science Standard 2E - Students know DNA (deoxyribonucleic acid) is the genetic material of living organisms and is located in the chromosomes of each cell.