<p>
	Key Ideas Introduced in this Unit:</p>
<ul>
</ul>
<ul>
	<li>
		Environmental data contain many variables and they are often linked</li>
	<li>
		A graph is a visual representation of data analysis and a useful tool in science</li>
	<li>
		Judging whether or not differences are meaningful</li>
</ul>
<h3>
	<a name="TOC-Concepts-and-Relationship:"></a>Concepts and Relationship:</h3>
<ul>
</ul>
<p>
	Students will:</p>
<ul>
	<li>
		Learn to create meaningful graphs</li>
	<li>
		Learn to read different types of graphs and understand what they show</li>
	<li>
		Analyze data to determine relationships or differences</li>
	<li>
		Learn to interpret data</li>
</ul>
<h3>
	<a name="TOC-Vocabulary:"></a>Vocabulary:</h3>
<ul>
</ul>
<p>
	Learning the vocabulary to talk about data can be difficult. Here are some key terms you might begin to establish with your class, as you work toward final presentations:<br />
	&nbsp;</p>
<ul>
	<li>
		<b>Mean </b>-- for our purposes, the average. Add all the values and divide by the number of values. Statisticians will tell you there are lots of types of means, but this isn&rsquo;t relevant to our level of inquiry.</li>
	<li>
		<b>Median </b>-- the middle value in a set of numbers. For example, of 3,4,5,6,7 &ndash; 5 is the median, the middle value.&nbsp;</li>
	<li>
		<b>Variability -- </b>the spread of the data&nbsp;</li>
	<li>
		<b>Meaningful differences -- </b>when comparing groups, we want to know if the differences (if any) are large enough that they mean something in the real world. For example, if someone offered you $100.00 and someone else offered you $100.01, you really wouldn&rsquo;t care which you picked &ndash; it&rsquo;s just a penny. But, if someone offered you $100.00 and someone offered you $120.00, you&rsquo;d probably want the $120 &ndash; it&rsquo;s definitely more and the extra $20 makes a difference to you. Our data plots give us tools to help make the judgment whether a difference is meaningful or not.&nbsp;</li>
	<li>
		<b>Correlation -- </b>the degree to which two things are related. For example, if bigger fish have more mercury, and this pattern is clear, we would say that mercury concentration and fish size are correlated. We talk about strong or weak correlations &ndash; strong correlations mean the relationship is very tight, whereas weak correlations mean that there&rsquo;s a lot of variability in the data. Things may be positively correlated&mdash;as one thing gets bigger, the other gets bigger too) or negatively correlated&mdash;as one thing gets bigger, the other gets smaller. See the activities below for more detail.</li>
</ul>
<div>
	<h3>
		<a name="TOC-Student-Prerequisites:"></a>Student Prerequisites:</h3>
	<ul>
		<li>
			The purpose of a graph and what it looks like</li>
		<li>
			Basic math skills (calculate an average, etc.)</li>
	</ul>
	<h3>
		<a name="TOC-Misconceptions-about-mercury:"></a><font size="3"><b>Misconceptions about mercury: </b></font></h3>
</div>
<div>
	<ul>
	</ul>
	<ul>
	</ul>
	<ul>
		<li>
			It doesn&rsquo;t matter which is the X axis and which is the Y axis</li>
		<li>
			Data can be put on a graph in any order</li>
		<li>
			Graphs are only used in math class</li>
		<li>
			All the data given should be plotted (as opposed to judging and choosing relevant data in a complex system)</li>
	</ul>
</div>
