Bar Chart and Block Diagram
Data & Statistics · Year 1–Year 5
Build a bar chart with the class. The same data as blocks, in one tap.
About the bar chart
A chart the class builds rather than one they are shown. Ask how everybody got to school, press the Walk column at eight, and there is the bar. Pressing sets the bar to the height you pressed at, because counting a show of hands is "eight walk", which is one press rather than eight.
The same numbers switch to blocks in one tap. At a scale of one that is the block diagram of Year 1 and 2, one square per child. Turn the scale up and each square is worth 2, 5 or 10 and it is a pictogram, with the key drawn above it. Nothing about the data changes when the picture does, which is the whole point: it is the same information shown two ways.
A part-worth remainder is a narrower square, not a whole one. Pictograms in books use half symbols and the idea is the same, but a symbol drawn full for a remainder of two is the picture telling a class something untrue, and that is the one thing a chart must not do.
The axis never moves. Ten gridlines always, so the top is ten times the step and a bar of the same height means the same number from one lesson to the next. Charts that fit their axis to the data are the usual thing and they shift every bar every time a number changes.
How to use it on your whiteboard
- 1Press a column at the height you want, or drag to sweep the bar up and down.
- 2Categories opens the list. One per line, up to six. Renaming one keeps its bar.
- 3Axis steps sets the gridlines to 1s, 2s, 5s or 10s. In Blocks it sets what one block is worth.
- 4Numbers hides the count above each bar, so the class has to read the axis.
- 5Zero puts every bar back to nothing, ready for the next survey.
Questions
- Why does pressing set the bar instead of adding one?
- Because counting hands gives you the answer, not a running total. "Eight walk" is one press at eight. Dragging does the same thing continuously, so you can pull a bar down as easily as up, and pressing the same place twice always means the same number.
- How do I make a pictogram?
- Switch to Blocks and set the scale to 2, 5 or 10. Each square is then worth that much and the key appears above the chart. A leftover part of a square is drawn narrower, so it shows the part it really is.
- What happened to my bars when I changed the step?
- Turning the step down lowers the top of the axis, and a bar taller than the axis cannot be drawn. Bars that no longer fit are brought down to the new top, in one step you can undo. Turning the step up never changes a bar.
- Can I add a title or label the axes?
- No, and that is deliberate. Typing needs a keyboard, and a teacher at the board has a finger. Naming the categories is the part a class needs, and that is in the Categories list.