A Teaching Practicum
Here, a boy has spotted what appears to be a discrepancy in the periodic table. The figure for the relative atomic mass of elements in the textbook is a decimal figure rather than a whole number. The way I set up the lesson's activity assumed the atomic mass of an atom of an element is a whole number obtained by adding the number of protons and neutrons in an atom. Actually, the boy has noticed something that is very important: that elements have isotopes with different atomic masses - and the relative atomic mass figure in the textbook is a proportional average of these different isotopes. The benefit of setting open-ended problems is that it allows students to pursue knowledge in new and sometimes surprising directions. This student is onto something very interesting.