PYP unit How the World Works, Counting Simple Machines in your home Counting Simple Machines, Tally Chart, Bar Graph This is a quick activity for a center, small group, or whole class. Students count simple machines in their house, record each items, create a bar graph using the data, and analyze the graph. It could be used as an assessment as well. Numeracy: Tally and bar charts Being able to make sense of data is an important skill. Tally charts are used to collect data quickly and efficiently