Material Engineers Part 2

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Objective

SWBAT test and explain which material demonstrates the selected property the best, based on measurable data.

Big Idea

Material Engineers use measurable procedures (fair test) to test materials for absorbency, hardness and flexibility.

NGSS Connections and Class Preparation

30 minutes

This is the 2nd part of a lab where students work as material engineers to test and rank materials for absorbency, flexibility, and hardness.

NGSS Standards

2-PS1-1 Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties. 

Students test and rank materials for specific properties.

Science Practices

- Planning and Carrying Out Investigations  (SP 3)

Students make observations and collect data to compare how well different materials exhibit a certain property.

- Analyze and Interpret Data (SP 4)

Students review their data to determine if they can answer their question and if their hypothesis was correct.

- Using Mathematics and Computational Thinking  (SP 5)

Students are exposed to the idea that measurement can be a way to make observations and in math use their data to build simple bar graphs.

Lesson Preparation

Review student ideas for testing materials, consider refining the notes so that it easier for the students to follow.

Gather 'testing supplies - This will depend on how students want to test, possible materials needed: small cups, washers, string, tape, graduated cylinders, water in small containers, eye droppers, nails, pennies, rubberbands

Students received their lab worksheets in the last lesson.

Question for the Day

5 minutes

Science starts with a question, usually written on the board. This allows students time to consider today's topic before the lesson has officially begun. I have established this routine with the kiddos to keep transition time short and effective and redirect student's attention back to content while allowing time for focused peer interaction.

Question for the Day: What materials are in a pencil and how do these materials' properties help the pencil do it's job?

I have drawn a pencil on the board ready to label with material, its property and purpose.

I point out that this is a 2 part question Then I invite the students to turn and discuss their ideas.

When everyone has turned to face me, I call on volunteers to help label  the materials used in a pencil and the important property of the material that helps it do its purpose for the pencil.

"Material Engineers test materials and help manufacturers choose the best materials for the product's purpose. Today with your team you will plan your procedure and test your materials to decide which material is the best for each property."

"When I say go, teams, please take out the lab papers that you started yesterday and move to your lab station. Review the materials you selected and your hypothesis. It is o.k. to revise your work."

While teams are getting settled and reviewing their lab, I project the students' testing criteria from the last science class.

In the last science class, students' ideas for material criteria and testing the materials for given properties were noted on the board.

Students used key words, from the property definitions as criteria. These words were circled and reviewed. I projected their ideas for the flexibility criteria.


Testing 1, 2, 3

40 minutes

I project their ideas and use this time to help students articulate the steps for testing and the materials they will need. I demonstrate how measurements can be taken and the supplies they can use to help them with their testing.

Students' ideas for testing are noted on the board. 

Possible methods:

absorbency: Place material in a small container. Pour one cup of water on the material. Wait 30 seconds then squeeze the water out of the material into a graduated cylinder. Write how much water was squeezed out of the material.

flexibility:  Tape one end of the material to the edge of the desk, allow 3/4 of the material to extend out, be sure the same amount extends out for each material. Hang a 100 g weight from the end of the material and measure how much the end of the material bent from its neutral position

hardness:  Scratch the material with a penny (mohs 3), if it can be scratched, then the material has a score of 3 or lower. If the material cannot be scratched with a penny try to scratch it with a piece of quartz (mohs 7). If it can be scratched then the material has a score between 4 and 7. If it cannot be scratched by the piece of granite, then the material has a score between 7 - 10. I have labeled the quartz so students know that it is not one of the materials to be tested.

The teams write the procedure steps in their lab packet.

When I review their lab procedures, I will be checking if most steps were written in a logical order and if they include the what to measure for the property.

As teams write their procedures, I place the testing supplies and material tubs on the back table.

I chose not to place the material tubs at their desks until the procedures are noted to encourage students to complete this step and to keep students from getting distracted by the materials.

I walk around the room to check that teams are clear about their tests and how they will measure and record their data.

I direct teams to select one of their members to pick up their material tub and testing supplies for their first property test.

Teams start their testing. Teams are performing 3 tests, testing 3 materials for each test.

I circulate around the room, checking that students are writing observations, and measuring accurately. I also start discussions to help students think about what products may need this property. 

Once I see that teams are on task and have a good idea what they need to do, I will take a couple of minutes to sit with teams as another member.

I have noticed that some students are not fully engaged when working in a team. I hope to be able to encourage their participation by asking questions and assessing what may be causing these kiddos to choose to not be as involved with the group. 

Results and Conclusion

15 minutes

When teams complete their testing and written their results, ranking the 3 materials for each property, I direct teams to bring their lab booklets and meet me on the rug.

I ask each team which material got the highest ranking for the property tested. Students use post its to show the team's results on a property bar graph. Teams write their names on the post-it place it over the material title.

When students review bar graphs in math I will use our material property bar graphs as an example.

"Sometimes it helps to show our results in a bar graph. It makes it easier to see the results. What questions does this bar graph answer? What questions does it not answer?"

The students share their results and help to create bar graphs for the other 2 properties. 

After the discussion, teams put away their supplies and materials and place their tubs on the back table. I collect their lab papers.

I will be checking the lab booklets for completeness and accuracy with measurements; procedures are clear and in a logical order and data has been written for each material. 

"We have been working in teams often in science and many times you are working together to test and write your observations in a team booklet. I would like to hear from you on how well you think you all worked together. 

"For your team exit ticket, you will complete a group checklist, to give me an idea on what you think went well  and what you could work on."

I am using the checklist to encourage self reflection on team participation.