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Data Representation

Teacher/Instructor Devorah Goldblatt
Devorah Goldblatt

Case Western Univ., summa cum laude
Perfect scorer on the SAT & the ACT

Devorah is the founder of Advantage Point Test Prep and the author of the book “Boost Your Score” The Unofficial Guide to the Real ACT.

Welcome to data representation passages. In this episode first we are going to talk about what to expect on a data representation passage then we are going to talk about some really fabulous strategies so you can nail this passage type on test day. And last we'll do an example together so you feel really really good about it. Let's get started.
Let's do a quick recap about data representation passages. First we are going to see three separate data representation passages on the ACT science section. You're also going to have five questions on each of those passages for a total of 15 questions. Okay and what are data rep? Well, what they are is just a little blurr and then usually a big chart or graph and then the five questions will be about what's on that chart or graph. Let's look at an example in case you don't remember.
So here we go, I have a little intro to a graph or chart. Next we've got this really big scary looking chart but don't worry we've got great strategies and we'll talk about what to look for.
Strategies for the data representation section. Let's take a look. First, this is very exciting. The harder the diagram chart or tables look, the easier the questions are going to be. It's such a great feeling so if you're flipping through and you're looking oh my God, this is a data rep, this passage looks awful and by passage I mean really the table, the chart or the graph because that's mostly what's going to make up a data representation passage. And it looks terrible and maybe there's some really weird relationship portrayed you're not sure, don't worry, and actually the harder it is or the harder it looks the more excited you should be about answering the questions because the questions will usually be really straight forward and just have just you read straight off that table and chart so remember the harder it looks, the easier it will actually be to answer the questions on the data rep passage.
Next, don't read the paragraphs or look at the diagrams. We talked about that for research summary. You'll have an intro before your big chart or graph, sometimes it's huge sometimes it's short, either way you can save time by knowing you don't have to read it all. The questions are all going to be about things you can pick up straight off of the tables or the chart.
Last, really analyze the charts and the graphs. Exactly because that's what the questions are going to be about. So let's talk about what are you going to look for when you analyze the charts and the graphs. First, what are they measuring? So take a look at it and say if it's a line graph, what's the X axis? What's the Y axis? What are the labels here? Just basically what's going on?
Next, are there significant trends? Are there patterns that really stand out to you? As one thing increases, does the other thing decrease? Do they both increase? Do they both decrease? I'm sure my hand motions are so helpful in portraying this relationship but really, think about, what's the relationship here? because they'll always ask about that on the ACT.
Last, how do the tables and charts relate? Sometimes it's just one big chart or graph, sometimes it's two next to each other for a data representation and then you'll have to ask yourself, how does the first one relate to the second one because they are always about the same thing so there'll always be a relationship between them and there'll always be a question about that relationship. So those are all the strategies that you need to tackle the data representation passages. You're going to do a great job. Let's keep going, we'll look at a real example and we'll see how these strategies apply.
Here's our data representation passage. So you see, we've got our intro here, kind of a long paragraph describing what we are going to see in the table. Remember, we don't need it, let's skip it. What we need is this table and we are going to look for things that we talked about before, things like the labels and things like the trends. Here, there isn't another table along with this question so we don't care about how they relate to each other, how different tables relate because we only have one table. So we are just looking for labels and we are looking for trends. Labels, what do we have happening here? Well concentrations in sediment. Concentration of stuff happening in sediment. Concentrations of what? SO four two, S two. It doesn't matter if you have no idea what these are, they are not going to ask that. They'll just ask you, just for these little titles here and you'll just have to relate information off the table. So we have a bunch of different elements or chemicals or something, we don't even care, we just have different titles along the top and we are tracking the concentration of those particles. Then here we've got depth and remember to look for trends. It looks like the depth is increasing from zero to 20 centimeters. And then we've got temperature, the temperature seems to be increasing too so by the way we have our first real relationship between different factors as the depth increases the temperature appears to increase as well. What about pH? We've got pH here too and it appears to decrease. Okay that's another relationship, so as the depth and as the temperature increase; your pH is actually decreasing.
Now let's look at these particles that we talked about. So we've got them over here, any relationships going on here? Any trends that look important? Let's look at the first one. It seems to just be decreasing as you go deeper and as you get hotter. This one seems to be increasing, CO two appears to be increasing and then decreasing. that might be important, it might not, it's good just to note it. FE three plus, whatever that is appears to be decreasing as you get deeper and hotter, FE two plus just increasing the whole time and then you have O two which decreases to zero and then stays at zero, that might be important. Great so we looked at the trends that are happening in this table and we looked at the labels. Let's tackle the questions.
Question one: 'the concentration of which of the following ions and dissolved gases is constant for sediment depths of ten centimeters or more?' Okay so which of these ions is constant, is staying the same for all depths past ten centimeters? Let's look, past ten what's staying the same? O two, we talked about this, so O two is the only one that's not changing, it's staying constant after ten centimeters, perfect. So D, oxygen, O two would be the correct answer here.
Let's keep going, next. 'As the temperature of the sediment increases, the pH level of the sediment does what?' This was a trend we noticed as well, what happened to the pH as the temperature increased? Let's look, so as the temperature increased, we said the pH decreases. That's easy again straight off this table so let's answer this question. So as the temperature of the sediment increased, the pH level of the sediment decreased. Great let's keep going.
Next: 'When the concentration of sulfide in the sediment is zero parts per meter'. Okay we don't really care what this means, it's zero or whatever is being measured. What do we know about the sediment? And here we've got to kind of pick out the answer choices to see what are they looking for here? Well they are asking us the sediment is acidic, the sediment is near the top; the sediment has no dissolved oxygen or has a temperature of five degrees Celsius. So what's happening to the sediment with regard to how acidic it is, with regard to its depth, with regards to its temperature when your sulfide is zero, your S two minus, let's take a look. So when we have S two minus, what's happening? Our depth is zero and our temperature is four and our pH is about seven. Let's see if any of that helps us. Is the sediment acidic? We don't know, we are not sure and we don't really talk about that. The sediment is near the top, hold on, depth. We said that depth was zero at that point and remember depth at zero, that's going to be at the top because as you go deeper you're getting towards the bottom so in this case B would be the correct answer.
Great, let's keep going. Next: 'Measuring sediments from five centimeters to 20 centimeters decreases the levels of Ferric Iron, FE three plus by what?' So now we care about amounts so we are looking from five centimeters to 20 centimeters. We want to know how is the FE three plus decreasing by what amount. Let's go back and look. So here we go, we are looking for FE three plus and what did we say we said from five to twenty? What's happening here? From five to 20 of our FE three plus, it looks like it's decreasing from three to point five. Okay so that's a difference of two point five. And here we go, not by one, not by one point five, or by two but by two point five ppm.
Finally, last question: 'A certain type of bottom dwelling microorganism thrives under the following environmental conditions: low concentrations of FE two plus, high concentrations of O two and a neutral pH'. Based on the table, at which of the following sediment depths would one most likely find this microorganism. This is a lot but we'll pick it apart quickly. If a microorganism lives best when you've got low FE two but high O two and a neutral pH, where would it be living? Now we didn't really talk about what a neutral pH is and that probably is something you would have gotten from reading. But you'll see actually you don't need that piece of information here; you don't need to know about gases and bases, which is what pH is about. We are going to have enough information just by looking at the low concentrations of FE two plus and the high concentrations of O two. So where do we have low FE two, high O two, at what depth? So we are looking for low FE two but high O two. Probably here because this is the place where your FE two is the lowest, we talked about that trend, it just keeps going up after this and the O two is the highest here, we talked about that trend too. After that it's just going to decrease. Great, so if we go back to this question, it will be at zero, at that surface, that it's going to be where this bottom drawing microorganism is most likely to live. That's it for a real data representation passage so hopefully you feel really good about this passage type now. We practiced using all those strategies we talked about on a real passage and now you'll know exactly what to expect on test day.
We talked about how to focus on the charts and the graphs because that's what's important, that's what the questions are going to ask you about. We talked about what to look for in a chart or graph, all the things that you need to be paying attention to and last we did a practice data representation passage and that's why you needed to keep practicing and the more you practice the more you're going to feel really great about data representation passages on test day.