Course Guide - USAID Teacher Education Project

Unit 4 Information HandlingWeek 1 Session 2: Graphing in the Primary Grades1. What are the important concepts?a) Tally marks, pictographs, bar graphs, and line plots can only be used to displaydiscrete, not continuous, data.b) Tally marks are a simple way to record information visually and then assign anumerical value to the tallies. Each item counted receives one mark; the cross markneeds to be included in the count so that each set of tallies equals five.c) Each icon used in a pictograph frequently does not represent a single count.Rather the icons usually refer to multiples of numbers, such as 5, 10, 100, etc.Because of this, there needs to be a key accompanying the graph that indicates howmany each icon stands for.If, for example the key is 1 icon per 100 count, a half icon can be used to denote 50.Also if multiple icons are used, they should be the same size to make the graph easyto interpret.d) Bar graphs are a visually strong communication device when kept simple. Theyalso can be used to show two data sets side by side as in this illustration.A problem with bar graphs, however, is that they are often truncated. When the barsdo not begin at 0, the height difference between the bars can be misinterpreted as inthis illustration.