For this project it looks like students dipped a piece of black yarn in watered down glue and then laid it down on a piece of paper to create an interesting shape. Then around the outside the students decorated the paper with patterns and designs, leaving the inside of the shape blank. This would be a great project for teaching about negative space with young students.
A great way to reuse caps, boxes, and various other containers, use them for printmaking! Students dipped various shapes and sizes of containers into tempera paint and used them to print on a sheet of paper. The designs were quite interesting, especially in the cases where some of the colors overlapped or a container didn't print fully.