Bar Graphs represent data visually as a series of bars. They are often presented to students in formative assessments. Teachers rarely take the time to create graphs from data for assessments or lessons. I didn’t use them at first either. Creating graphs is time consuming. I needed to do something because my students often missed easy problems when it came to questions from a graph or table. I was often surprised because we covered them during practice for the larger state assessments. It wasn’t until they started to develop their own that they began to make the crucial connections.
To be honest I wasn’t thinking of increasing their test scores with the development of graphs from data. I ran out of paper and ink one day and needed an alternative way for them to analyze information from a science experiment. I started with ordinary computer paper and a ruler. I walked them through the process of creating a bar graph. It took most of the class period. I didn’t think much of it apart from a simple exercise with students. The second time around it was easier for them to create a bar chart because they understood the fundamentals. I think they really liked coloring in the chart. Being the elementary school teacher that I am I promptly posted them in the hall.
I continued to create charts with students from bar graphs to line graphs. I also tackled circle charts when they understood percentages. It provided a great opportunity to reinforce the concept of percentage in a graphic format. The year came and went. The state assessment came and went too.
That summer I was given the class results for the state assessment. My class scored a little better than last year in math. It wasn’t until we took a closer look at the scores the following year. It was part of what we did as a national Blue Ribbon school. I noticed that most students answered every question dealing with charts correct. I was no dummy I thought this was something attributable to randomness or the specific class for that year. Each year’s class is different. No two are exactly alike. It was the class not me!
I proceeded to continue to manually create charts with students. I thought might prove to help them do better on assessments. I wanted to see the evidence for myself during the year. I developed a series of formative and summative assessments that included graphs and tables. I threw some of the hardest questions I could at them and they sailed through them with ease. Came the next state assessment and I received the same pattern of success. Their scores were perfect when it cam to questions dealing with table and chart information. Cool, I kept doing it every year and their test scores were always top notch.
The key lay in their understanding of how charts were created. They were able to make connections to the numbers that were represented in the graphics. They learned how data was collected and how it was represented by tables and charts. Their understanding of how circle charts are developed lean to another unintended result. Their scores on questions related to percentages went up too. They understood how percentages related to the whole. They understood how percentages were derived from totaling and dividing to form the circle graph.
Students began to understand how rounding worked. It was a domino effect. To getter a better result for percentages and circle graphs they needed to understand how rounding affected the slices in the circle graph.