Density unit Day 10 -Final day, revisit salad dressing

The only thing I did today related to the density unit was to give the final salad dressing assessment.  I had them wright the answer under their original answer in the lab notebook.  As is the case before, I gave the "Mrs. Leyeer question" to my first period question and the Page Keely style one to the rest of the classes.  I will bring some of the students responses to the meeting.

From here I will start to discuss the density of solids and also talk about Buoyancy as a force.  I have many other activities to finish out the density unit, but will miss the "flow" the last two weeks (pun filly intended).

Density Unit Day 9: wrap-up

Periods 1 and 2  I experimented with the order and by P3, I came up with the following:

First I had the kids draw a diagram of how you find the density of a liquid.  I got a bunch of different answers, but mostly got a comic strip style, step by step diagram of what you do (mind the volume, find the mass etc.).

Then I told the kids to find the density of water.  I had 3 different size graduated cylinders on the desk (1/3 had a 25ml, 1/3 had a 100ml and 1/3 had a 500ml).  The students struggled a bit, but for the most part the, once their mistakes were pointed out, they got on track.  very rarly did the students not know what to do.  I checked their answers, and had them type it in the computer under their group.  The purpose of this was to:

1. Assess the process skills on how to find the density of a liquid
2. show them that the density of water is 1g/ml
3. show them that the amount of liquid does not change.

We looked at the numbers, had a discussion about size and density, and I tied it back to the Cartesian diver answering the question "How dense are the water particles?".  I also told them to look at the data tables and try to guess which liquid was water.  

I then posted a table with a bunch of  liquids and their know densities,  and told them to use their notes to try to determine whet the other liquids were.  I took answers verbally in the Claim/Evidence format (i.e. Claim: the green one is corn syrup.  Evidence: it has a density of 1.32 and it smelled sweet.) Link to table: https://docs.google.com/present/view?id=ddhqzk34_57rdspx2dw

Then I attempted to layer all 6 liquids as they described them (with some success...see below).

The
Density
tube of
SCIENCE!!!

Density Unit Day 8: Mystery Liquids

Fig. 1

  I got 2 new solutions (see fig. 1):

• Salt water (dyed Black, although it looks green) - made by heating 1000ml water in the microwave, adding a TON of salt, and mixing until all the salt is gone that is going to be gone, then pouring it into another container, leaving the salt behind.
• Baby Oil (not dyed, left clear)- bought at CVS

I told the students that they needed to determine where the new liquids would fit into the existing layers.  In order to do this they need correct numbers form the previous lab.  I had some of the liquids out for students to redo or finish that lab.

Period 1 I left it relativity open, I said that all I wanted was a Claim (about where the clear and the Black  would fit into the layers) and Evidence (using numbers).  Most everyone started to make a data table right off the bat, and I have very little problems.  2 groups misunderstood the directions and simply stated how the clear and the black would layer. almost everyone finished and got stamped.

Period 2 I gave them a little more structure in that I had them write "Claim" and "Evidence" on their paper, and I said that I wanted a data table (I think?).  Some put the data table below their Claim And evidence, while others added on to their data table form the previous activity.  Some just wrote their data at the bottom in no table, but provided data in their claim. almost everyone finished and got stamped

Period 3 I gave them given more structure, in that I said that I wanted them to have a data table at the bottom. Most finished and got stamped.

Issues:  There needs to be something for the students to do.  some students are breezing right through this and then they are done.  others are still struggling with the lab from the day before (which they need) and it takes them longer.  The students that are done have nothing to do (which could mean problems).

NOTE: the baby did not float on alcohol (did we think it would?) not a huge issue.

Tomorrow I plan 2 things, 1)demo the placing of the 2 liquids, and 2)give them a list of the known densities for the liquids (plus some others) and have them try to guess the liquids.

Density Unit Day 7: Catch-up and Double alcohol assessment

Today  I let the students finish the lab form yesterday (finding the density of the liquids) and stamped off the complete ones.  I also gave the kids a chance to earn stamps from previous labs.  While this was happening I sent them up one at a time to enter their density data into an excel program that automatically finds the average. this led to a discussion about "does density effect layering?"

with 10 minutes left in class, I gave them the "Double Alcohol Assessment".  (link below)
https://docs.google.com/document/pub?id=1LkizaeTJoSqM7kDCC-MlKr7wnJNKyI-ePwrlUyWFJbg

Density Unit Day 6: Finding the density

Students doing the lab

Today they are finding the density of the 4 liquids.  I started the day reminding them what we did on Friday,  (we had 3 "theories" as to why they layered...order, we have evidence against...Thickness, we have evidence...density, we do not yet have evidence).  I then did a question of the day where the students got to choose which qeastion they answer 1) how do you find the density of a liquid? or 2)How do you find the volume of a liquid.  This led to a discussion/review.

I posted the mass of the Graduated cylinder on the board and told them to make a data table in their lab notebook that has color,mass,volume, Density and the students worked in pairs to find the density of the objects.

A good lab notebook with typical results

Some groups finished, some did not.

Some small issues:
I had to have a discussion about rounding, most of the students were fine, however they did not know what I meant by "round the density to the nearest hundredths", instead I had to say "round to 2 places after the decimal point.".

I also had a discussion about he units for density.  I still had kids ask what the unit for density is, I do not think they understand the concept of "keeping the units when you multiply or divide measurements".

Many did not subtract the mass of the graduated cylinder. This was evident by their answers. Once they were reminded they were fine.  1 or 2 groups were very confused and I had to explain it to them.

Every once and a while, they would do volume divided by mass.  Again, This was evident by their answers and was easily corrected.

All the above issues increased as the day went  on (attention?) and with lower classes (higher amounts of Sp. Ed. students)


Tomorrow I plan to let them finish/check their work and write a claim about their data.

Density Lab Day 5: Layering all 4 liquids

The layered liquids

There are some regular "Friday " things that we do, so this left about half the period for the activities so it was a perfect day to let the students layer all the liquids in one test tube. One mistake I made is I did not habe them write their "final" prediction (from yesterdays whiteboard) in their lab notebook.  As a result they had to remember their prediction from yesterday.

The students had to get thbeir supplies and pour the liquids in.  the "prediction" piece is turning out to be a problem because it strengthens the notion that the layers have to do with the order you place them.  some groups predicted wrong and saw the liquids sink und other liquids.  (some of the justifications are precious...because its stronger or because i poured it wrong)  I even saw one group pour the red in before the blue and the yellow and they still got the "correct" layering.  I tried to point out that everyone in the room has the same layers, and in p2, i even showed them what would happen if you put yellow on the bottom, then green, then blue, then red.

I asked them " why did this happen?" and eventually I got density out of them (it is the unit we are on after all!).  Then I said that you can quantify density and asked for prediction (more than, less than) about the density of the liquids.

3rd period, I did not mention their predictions and just said tho add the liquids into the test tube.  this lead to more liquids sinking under other liquids, hopefully leading to them understanding that the order does not matter. Their is the exception of the red and the blue.  I talked briefly about how some fluids mix and some do not (referring to the salad dressing) and tried not to dwell on it.  this only happened to 2 groups, one group, the blue/red layer sunk under the yellow , leaving a small pinkish layer on top. I pointed out that (almost) everyone got the same layers, and asked why.  again, thickness came up and I was able to provide evidence against that because the yellow (thicker) goes on top of the blue (thinner).  When density came up i treated it as a possibility and discussed how we can quantify density and suggested that as possible rout we would want to follow...to gather the evidence for that theory.

I did the "Question of the Day" towards the end of class (after the layering activity above).  Today we did a quick-write, meaning the students write for four minutes straight in a given topic.  The topic was "what do you think about this weeks activities/labs?  What did you like? What would you change? What did you learn?  Below are 2 typical examples.  Note the use of the word "thicker".

I talked with Marie and we agreed that a more natural flow would be to have the students measure the density of the 4 liquids they have been working on.  ( the "poster" says to find the density of the mystery liquids...salt water and baby oil?).  Monday I will do that.

Supplies

Supplies purchased (for 5 classes of 29-35 kids)

• (5 x 16oz )80 oz Alcohol (need more for week 2)
• (3 x 32)96 oz corn syrup
• about 50 Plastic cups
• 60 oz oil

Not purchased (had in the dept.)

• Food coloring

Lab equipment

• 36 test tubes
• 9 test tube racks
• 9 test tube brushes
• 2 1000ml beakers to mix the water and corn syrup w/ the food coloring
• 36 50ml graduated cylinders
• 18 Trip. Beam Bal. (studs work in pairs)