Slide showing negative graph extracted from book demonstrating the 'Mean score in group of families of different sizes.' Slide shows negative graph extracted from book demonstrating the 'Mean score in group of families of different sizes.' X-axis is labelled 'family size' with numbers 1 - 13. Y- axis is labelled 'test score' with scale from 0 - 50. Title below graph reads: 'Fig, 5. Mean score in group of families of different sizes'. Late 19th to early 20th century