For KS3 Biology (maybe KS4) - Reproduction section. I printed these images onto 1 sheet of A4 and got my year 7 class to discuss and annotate each of the images. The first one showing a regular baby - they had to label. The second shows twins that appear to share an amniotic sack - so potentially (not necessarily) mono-zygotic. The third shows twins that are in 2 separate amniotic sacks (potentially?) so are di-zygotic. The fourth shows conjoined twins. The pictures brought out some really interesting questions and discussions from my class!