Student work
from the inquiry experiments

Golf ball journal

Students keep a journal in science class. Each day there is an Opener, which is a question or questions for students to answer at the beginning of class. In his journal, Student A answers the Opener, and then records the demo experiment the golf ball experiment. In the experiment, I pour 200 milliliters of rock salt into a one liter graduated cylinder. In another one liter graduated cylinder I have exactly one liter of water. I ask students to write in their journals how much water will be left in the "water" cylinder if I pour water into the "salt" cylinder up to the one liter line. There are a number of different guesses, from zero to 200 milliliters. I ask them to say why they guessed what they did. Student A guesses 150 milliliters. When I actually pour it in, 100 milliliters of water are left.

On the next page, Student A records the next part of the demonstration: I ask students to predict what will happen when I put a golf ball into the cylinder with the salt and the water. His drawing shows both before dropping the ball in, and after. He also labels the level of the salt after the water is added, and makes a prediction for the water level as well as for the golf ball. I ask for a prediction about what we will see in two weeks. I ask students to say why they predicted what they did, and we discuss their reasons, but I don't tell them to write down their explanations. In doing it this way, I am trying to find a balance between having them make a record of their predictions and observations, on one hand, and not having them write so much that they experienced this process as horribly laborious, on the other.

Quad quiz golf ball

Shortly after we set up the golf ball experiment, students take a "quad quiz" about prediction. In a quad quiz, students fold a piece of plain paper twice, making four quadrants. There are four questions, one for each quadrant and I give them one at a time, writing the question on the overhead and saying it out loud, and taking questions if it is not clear. On this one, three questions are about prediction and one is about drawing a labeled diagram of the experiment. (For the diagram, I showed them the actual golf ball, salt, and water set-up again.)

Revision of quad quiz

After they take the quiz, I photocopy examples of good student work from the other class, two examples per problem. On a later day, we look at them and discuss them together as a class. I ask students to choose one of their answers where they thought they did well, and to say what they thought was good about that answer. Then I ask them to choose one answer they can improve, and to write an improved answer. Students score their own papers on this first quiz, giving themselves one point for each completed answer, including each of the first four answers, the one where they improved one answer, and the one where they said what they thought was good about another. The examples I give them to look at are two different good answers, not one good and one bad. We discuss what is good about each one. After having written their own answer, looking at other people's work is a way of adding to their understanding of the problem. Student A revised his answer for number 3 by adding the sentence that is underlined in his original paper (see Quad quiz golf ball, the previous example).

Ice demo journal

After the golf ball experiment, the next experiment is the one where I show students two beakers of clear liquid and ask them to predict what will happen when I put ice into each one. Student B makes a labeled diagram, writes her prediction, and her hypothesis (the explanation for her prediction). I want them to go on record (briefly) before the ice goes in. After I drop the ice into the two beakers, she makes observations, and inferences (explanations for the observations). Student B already has the vocabulary for "dense." (Most students, at this point, did not have that word.) At this point, we discuss what is causing the different behavior of the ice. Student B said "she added a chemical," which is a pretty good guess, although she doesn't say what chemical she thinks it is. I ask students to ask a new question, and Student B asks about what would happen if we used hot water.

Journal prediction for many liquids

A week later, I bring to class the liquids students had guessed might be in the second beaker, the one where the ice sank to the bottom. I set up six glasses of liquid, and ask students to predict, for each one, whether the ice will float or sink. This is Student A's table of predictions before the ice went in, and observations afterwards. The first part, the Opener, is a fill in the blanks exercise where students put in the missing words: prediction, hypothesis, observation and inference. Student A's predictions are not all correct, and I continually emphasize that it is perfectly OK to have an incorrect prediction. The important thing is to have thought about it, and to have a reason for your prediction. His inference is that the alcohol might be less dense. Most students are not thinking of this in terms of "density" yet.

Quad quiz ice in alcohol and water

After the experiment with the six different liquids, we have another quad quiz. I set up a demo experiment: I pour 300 milliliters of alcohol into a one liter graduated cylinder, talking about what I am doing as I go along. Then I have some water in a beaker, and add a little blue food color so that the water and the alcohol will look different. I layer the water underneath the alcohol in the cylinder by using a turkey baster as a pipette. For the first question I ask students to make a labeled drawing of the cylinder with the alcohol on top and the water under it. I tell them I am going to drop in a piece of ice, and question 2 is for them to make a prediction about what is going to happen, and to explain their prediction. Student C predicts correctly in question 2, but his drawing in question 1 doesn't correspond to his words. Student D talks about the previous experiment in her explanation. I drop the ice into the cylinder, and question 3 is to make an observation, and to explain the observation. In their explanations, Student C and Student D both explain the observation by writing about the previous experiment. The last question is to explain the difference between observation and inference. I use the word "explanation" with the word "inference" at this point, so that the unfamiliar word always came with a familiar one, and so that the unfamiliar one will seem less foreign.

Revision of quad quiz

After the quiz, a few days later, we look together again at student work. I choose papers from the other class so no student will feel embarrassed about having other students comment on his or her work. Again, I choose answers that I judge to be good answers, not ones where I am asking students to say that one is good and the other is bad. I want them to look for what is good in each of the answers, to get a sense of what other students are thinking, after having answered the questions themselves. We discuss each answer, and then they get their papers back. The papers haven't been graded yet, so there is no teacher judgment about what they wrote. On a separate piece of paper, they are to write about one thing they did well, and why they did well. Then they are to revise one of their answers to improve it. I am hoping they will refer to what they have learned in the discussion for their revised understanding of the question. This revision is from Student E.

Is alcohol heavier than water? journal

When we were discussing why the ice cube sank in the alcohol and floated in the water, one of the ideas (inferences) proposed by a student was that the water is heavier than the alcohol. For the Opener on a later day, I ask students to write down an idea for an experiment where we could test that. Student A suggests a viscosity experiment, which is a reference to the viscosity experiment we did in the sixth grade (click here to see the experiment). Student B suggests weighing the two liquids, and gives some directions about how to do that. In the previous discussion, we have talked about some ideas for what we might do. At this point, the students have had a chance to think about the ideas for a few days, and this is a chance to say what they now think will be a good experiment.

Is oil more dense than water? journal

After many more experiments, we do an experiment to find out if oil is more or less dense than water. Click here to look at videos of that experiment. Student B records her prediction before the experiment, her hypothesis, and her data as she weighs the graduated cylinder and the oil. The prediction about whether the oil will freeze is for a new experiment. We are going to freeze the cylinders with the oil in them to see what happens. The next day, Student B answers the Opener, telling what we found out the previous day about the relative densities of oil, water, ice, and alcohol.

Quad quiz oil and water

The third quad quiz is about the densities of water, oil, and ice. Like the second quad quiz, it is something the students have not seen before. They are being asked to predict about the floating and sinking behavior of these substances based on the measurements they have made in the lab a few days before. Student F draws the diagram for the first one and makes his prediction based on the previous experiment, where he weighed oil and compared it to the weight for water. In his inference he talks about densities and, interestingly, says that "this experiment proves that oil is less dense than water." So he is seeing it as a second experiment about the density of oil, and the results of the two experiments agree. For the ice, he predicts that it will float on top of the oil, based on the numbers, but when I drop the ice in, it stays in the middle of the oil. Student F says that the densities are almost the same. Student G predicts that the ice will sink to the bottom of the oil. When it floats in the middle of the oil, he concludes that it is more dense than the oil, which doesn't quite match his observation, although it matches his prediction. After the quad quiz, the ice gradually melts and sinks down to the bottom of the oil. That surprises me, and I have to think about it, but I realize that as the ice melts and turns to water, its density increases.

There is a fifth question to this quad quiz, on the back. I ask students how a prediction and an observation are similar and how they are different. Students find this question much more difficult than I thought they would. A few days later we again review student work, comment on it, and write a revision.

Data for everything

As we measure water, alcohol, ice, oil, and the graduated cylinders, I keep an overhead sheet where I record the data the students collect. We keep referring to these numbers as we talk about the relative densities of the substances. For each substance, we have weighed 44 milliliters of the substance in a graduated cylinder. Since we are comparing relative weights, I don't worry about the fact that the cylinder is included in the measurement for each one. During the experiment where we weigh the oil, we also weigh the graduated cylinders so we can subtract and get a net value for each substance.

Table of everything

I write an assignment to help students understand what numbers we are averaging and why. We are near the end of this particular series of experiments, and we are able to put the values we have determined for each substance into a table. The table is a good way to compare the values, and students understand what the numbers mean because we have spent many experiments gathering them, many discussions talking about them and going back to that same overhead where we have been recording all this data.

Student C makes her table with pictures of the substances next to the names, and she lists the substances vertically. Student A shows the work he has done to average the numbers, and he lists the substances horizontally. When the charts are first made, we don't have data for carrots (those numbers are added later), but students use the charts to help them make a prediction for how much the carrots are going to weigh, based on the carrots' sinking behavior in the graduated cylinder. Most of the time, we have weighed first and tested the floating or sinking behavior of the substance second. For the carrot, we test the floating behavior first, and then we do the measuring of the volume, and the weighing.