Eliciting students ideas about gas behavior

Activities:
1) Elicitation of student ideas.
Describe
 what
 you 
already 
know 
about 
how
 gasses 
behave.
(Think
 about:
 How
 do 
they 
move?
 What 
affects
 their
 movement?
 What 
is
 a 
gas?)
2) Explaining an oil tanker crushing phenomenon. Students 
watch
 video.
Unprompted 
they 
start 
thinking
 about
 why 
this 
happened.
Students
 then
 record
 initial 
ideas.
Students
 then
work 
in 
groups 
to 
draw
 before,
middle
 and
 after
 pictures.
3) Whole‐class debrief.
Students
 share
 posters 
of 
their 
initial 
ideas.
4) Homework:
Students
 did 
a
reading 
about
 the
 behavior 
of 
gases.

Discussion questions for teachers: 1) What general ideas do most students seem to have about the behavior of gasses? Which of these ideas can be built on? 2) How does Bethany uncover students’ ideas? What kinds of questions does she ask when students give incomplete responses or reveal an alternative conception? What does she do when she first enters a group/ exits a group?

Building an initial consensus model and linking together parts of the causal story.

Activities
1) Warm-up Yesterday you heard different groups present their ideas about why the tanker crushed. You also read about the behavior of gases as homework. What are 3 new ideas you have about why the tanker is crushing? Teacher reviews student ideas from previous day.

2) Making an initial consensus model. Teacher reviews student posters using 2 guiding questions: A) Make a list of what’s causing the tanker to crush. B) Does anything seem to be linked together? Does one thing happening seem to cause another thing to happen?
3) Pop Can Activity: Back pocket questions are used to a) help students link together parts of the causal story b) identify gaps in the students’ causal stories and c) help students begin to think about how they could further study the phenomenon.

Discussion question for teachers: In the video Bethany works with two groups as they consider the relationship between phase changes and pressure changes. How does she tailor her back‐pocket questions in response to each group’s line of thinking?

Explaining pop can crushing.

1) Warm‐up, Day 3. “How is the pop can similar to the crushing tanker? How is it different?”
2) Examining variables. Teacher helps students hypothesize about 5 experiments inspired by student ideas from the previous day.
3) Pop can Activity II. As students conduct experiments the teacher poses back pocket questions to a) help students link together parts of the causal story b) help students identify gaps in their causal stories.

• Experiment #1: Amount of water in the can
• Experiment #2: Temperature of the water bath
• Experiment #3: Amount of time on the hot plate
• Experiment #4: Volume of the can
• Experiment #5: Amount of seal

4) Warm‐up, Day 4. Teacher prompts students to consider 4 key ideas in their explanations. The warm‐up asks students to “Choose one of the following ideas and explain how it relates to the experiment you did yesterday.

• Temperature change‐ speed of molecules
• Temperature change‐ phase of matter
• Pressure inside
• Pressure outside

5) Complete pop can Activity II. As students finish experiments the teacher poses back pocket questions to a) help students link together 4 parts of the causal story.

Day 5. Think back to your experiment with the cans.State your results as a rule. How did changing the manipulated variable affect the amount of crushing? When _________________the can crushed more because ____________________.

Reporting out and connecting experimental findings. Teacher coordinates discussion of findings across groups. Teacher describes what happens and presses student to say why.

Discussion questions for teachers: 1) Record the questions Bethany asks, group them into conceptual categories, and then consider her reasoning for asking these rounds of questions in this particular order. 2) Which questions seemed to be most productive for helping students move their thinking forward?


Continues…

This video continues activities from the previous scenes…

Increasing content understanding about air pressure

Increasing content understanding about air pressure (as opposing forces) and relationships with volume, and temperature.
PV=nRT
1) Increasing content understanding about air pressure.
 Students 
struggled 
to 
reason
 with 
internal
and
 external 
air 
pressure.
Teacher
 reviews 
homework
 assignment
 about
 pressure.
Teacher 
has 
students
 show
 work
 to
 class 
as
 a
way
 to
 “work 
on 
student 
ideas.”
Then
 teacher helps 
students
 reason
 with
 forces
and
 pressure.

2) Balancing Act.
Teacher 
asks
 students
 to 
reason
 with
 number 
of
 molecules,
 temperature,
 volume,
and
 pressure
(in 
terms
 of
 pulling
 and
 balancing 
internal
 and 
external
 pressure)
throughout
 4
experiments.

Station
1
 Balloon
 Blow
up
Station
2
 Marshmallow
 vs.
 Pebble
Station
3 
Expanding
 Balloon
Station
4
 Balloon 
in 
Flask
3) Warm‐up, day 6.
Draw 
a
 diagram
 to 
explain
 why 
this 
tire
 would 
inflate.
Draw
 the 
air
 molecules
outside
 the 
tire,
 draw 
the 
air
 molecules 
inside
 the 
tire.
Use 
arrows 
to 
indicate
 where 
pressure 
is
 higher
or
 lower
.

4) Returning to air pressure experiments and explanations.
Students 
completed 
diagrams
 and questions for 
the 
air
 pressure 
experiments.

Discussion questions for teachers: 1) What are different strategies Bethany uses to plan for as well as in‐the‐moment work on students’ ideas? 2) What kinds of ideas do students wrestle with during the experiments? Do the conversations move beyond procedural talk? When, how?

Applying new ideas to a model

1) Warm up, day 7.
Students review air pressure experiments. Specifically the relationships between pressure and the a) number of molecules, b) volume and c) temperature.
2) Adding to the model. Teacher facilitates a whole class discussion about the information that needs to be added to their initial model. Then students work in small groups to add to their models of the can crushing for the experiment they conducted. NOTE: The teacher notices students are trying to apply ideas about kinetic molecular theory to the can crushing experiment. They reason with partial understandings about the speed of molecules, how the temperature influences speed, why the space is important to molecular movement. The teacher helps students link these ideas to the experiment but also directs their focus to a different but related underlying explanation (the number of molecules) to explain why the can crushes.

Applying new ideas to a model

Warm up, day 8
1) In response to how students were reasoning with molecules, the teacher designed a warm up to help students think about the number of molecules at each stage in the can crushing. “Say I started with 10 water molecules (X’s) in the bottom of the can and 20 air molecules (O’s) in the can and then I heated it up to boiling and let it boil for 2 minutes. Draw a picture of a can and mark where you think the X’s and O’s would be after these 2 minutes.”
2) Adding to the model. Students return to diagrams and continue to add information to their models using a checklist with key concepts for the students to include.

Discussion questions for teachers a) How is the explanation check list developed How is it used? b) Generally speaking, compared to days 1 & 2 how have students built on their original ideas? And what new ideas are they entertaining now?

Using mathematics to understand gasses

Increasing content understanding about number and speed of molecules and relationships with pressure, volume, and temperature.
PV=nRT
1) Warm up. The teacher asks a warm up that helps connect ideas about kinetic molecular theory with the gas laws. “When you flip over the can into cold water, describe what happens to the phaseand speed of the gas molecules (both X’s and the O’s) inside.”

2) Pressure and Collisions. Students talk about correlations between pressure and number of collisions on a container and then reason with three ways the pressure/number of collisions can decrease—the amount of space (V), the number of molecules (n) and the temperature (T). Students then look at these relationships in a computer simulation. http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=25

3) Can you compress water? Teacher helps student reason with the differences between air molecules and water molecules. Need to think about pressure of water in can puts on the can and why this is an important part of the explanation for why the can does not crush.

4) Return to posters to add new knowledge. Teacher highlights 2 parts of the explanation checklist that students are generally not attending to in their explanations. She also provides each group with 3 sheets of fill in the blank sentences to make sure students are reasoning with a full explanation for each of the 3 can crushing stages.

Discussion questions for teachers 1) Bethany adds an additional scaffold to the check list by giving students sentence starters. How does this shift the ways students participate in class?

Generalizing to the behavior of all gases

Piecing it all together.
1) Teacher facilitates whole class conversation of a full explanation of the tanker Generalizing to the crushing.

2) Review of learning. Teacher has students refer back to initial explanations. behavior of all gasses.

3) The Behavior of Gases. Teacher reviews general ideas about what influences the behavior of gases and bridges to scientific language. Then the teacher introduces the Ideal Gas Law.

4) Focus on correlation between P & V. Pressure Volume Student do activity with syringe and scale to Pressing students for evidence examine the relationship between P & V. Students graph results and talk about an inverse relationship. based explanations

5) Warm up, Day 11. Explain from data the previous day how we know that pressure and volume are considered inversely proportional.

6) Review lab and introduce Boyle’s Law. Teacher introduces the idea of P1V1=P2V2. Teacher asks questions that help students reason conceptually and mathematically with the equation. Students then record notes on a master table with the ideal gas law broken down in to 3 different relationships.

7) Volume and Temperature. Teacher introduces the idea of Kelvin by having students think back to volume and pressure lab and whether or not 0 pressure or 0 volume is possible. Students then do mathematical calculations to examine the relationship.

8) Warm up, Day 12. Your car tire ahs 10L of air and it’s 0 degrees Celsius outside. Later that day the temperature has increased to 26 degrees Celsius. What will happen to the volume of the tire? Why? 9) Review of Volume and Temperature. Students take notes on Charles’s Law. V1/T1=V2/T2.

10) Pressure and Temperature. Students take notes on P1/T1=P2/T2 and then do practice problems.

Discussion questions for teachers: 1) Thought experiment: Typically in Chemistry students learn each gas law and do calculations. Compare this to Bethany’s “concept first” approach. Also think about the difference between learning about a theory about the behavior of gasses versus laws.

Continues from the previous video…

This video picks up from the previous one.

Applying gas behavior principles to car engines

Applying gas behavior principles to car engines.
1) Warm up, Day 13. What are the gases in the engine? What gas(es) are present during intake, compression, combustion, and exhaust?

2) Engine Modification Challenge. Students select 3 modifications and describe why each modification helps a car have more power. They also need to describe why a pressure sensor is needed on tires. Students read background information on each modification and complete a fill in the blank form that helps students reason with P,V,T and n. tire pressure monitoring system bore out cylinders cold air intake high performance exhaust system intercooler nitrous oxide system turbocharger supercharger

3) Warm up, Day 14. Why is getting more oxygen into the engine beneficial? (Think about the combustion reaction).

Final interview with Bethany

Final interview with Bethany