Inquiry Science Lesson Plan 

Reflection # 7

Subject/Gr: Science (Gr.7/8)    Lesson Title: Experiment on Surface Tension

Teacher: Lila Gaertner

Stage 1: Identify Desired Results
Outcome(s)/Indicator(s)/Treaty Outcomes and Indicators:

FD8.2 Examine the effects of forces in and on objects in fluids, including the buoyant force.

g. Conduct a fair test to identify which factors determine whether a given object will float or sink, and discuss reasons why scientists control some variables when conducting a fair test.

 

Modified Indicator:

g. Conduct an experiment with a group of classmates to identify whether a paperclip will float or sink.

 Key Understandings: (I Can Statements)

 * Understand Buoyancy.

 * Conduct an experiment to identify whether a paper clip can float or sink.

 * Understand Surface Tension.

 * Work in a group as a team.

Essential Questions:

 1. What is Buoyancy?

 2.  If a paper clip is not buoyant, then how can it float?

 3. What is Surface Tension?

 

 

Stage 2: Determine Evidence for Assessing Learning
 –          There will be worksheets that the students will have to fill out as the lesson progresses. There are nine questions for them to answer. The questions will be pretty simple to answer if the students are listening and watching the screen for the answers. Once they have the first few questions one, they will be able to make predictions, answer questions after observing and then explain the floating paper clip experiment.

–          Students will also be assessed on their teamwork and ability to work in a group to try the experiment.

 

Stage 3: Build Learning Plan
Set (Warm-up, Focusing the learning):      Time: 5 mins

 Have the PowerPoint up on the projector, the POE Trifold Board displayed at the front, and the materials needed for the experiment laid out at the front before you start the lesson.

 Say: Today we are going to conduct an experiment to see if paper clips float.

 Ask: How many people think paper clips can float?

 Say: There are a few things we need to know before we do the experiment.

 Ask: What objects do you know of float?

(Boats, Ping Pong Balls, Beach Ball, Rubber Duck, Apples, Oranges, etc.)

 Ask: What makes it possible for objects to float? Why do things float?

(Things float when they are positively buoyant, or less dense than the fluid in which they are sitting. This does not mean that an object has to be lighter than the fluid, as in the case of a boat; objects just need to have a greater ratio of empty space to mass than the fluid.)

 Development:                                              Time: 30-35 mins

 What is Buoyancy?

 Buoyancy is the ability or tendency of an object to float in a fluid, which can be a liquid or a gas. This happens because fluid pressure increases with depth.

 Fluid pressure is the amount the molecules in a fluid that hit an object. If you go underwater, diving down deeper and deeper, the molecules are closer and closer together. Because of this, they hit you more. So the pressure gets bigger the deeper you go. If you put an object underwater, there will be more pressure on the bottom of the object than on the top, because the bottom is deeper underwater. And this creates an upwards force.

The upwards force that an underwater object feels is called the Buoyant Force.

POE (Predict Observe Explain) Experiment

 Predict

Are paper clips buoyant?

Do you think paper clips can float in water?

How do you think you can make a paperclip float?

 Materials Needed

  • Clean, dry paper clips (different sizes and shapes)
  • Pieces of tissue paper
  • A bowl of water
  • Pencil with an eraser

Safety Concerns

  • Do not splash the water out of the bowl.
  • If you spill water on the floor, wipe it up immediately to make sure no one slips.
  • Do not poke others or yourself with any of the paper clips.

 Experiment Time!

Explain to the students that you will be doing an experiment in small groups of five. Each group will get an instruction sheet with the materials needed, safety concerns and the procedure. Go through and ask the students predictions. The go over the materials needed and safety concerns as a class. Then break them up into their groups. Get one student from each group to come up to the front to gather the materials. They may begin once they have all of their materials. 

Procedure

1.      Fill a bowl with water.

2.      Try to make the paper clip float.

3.      Try dropping it in gently.

4.      Now, grab a piece of tissue paper and GENTLY drop the tissue paper onto the surface of the water so that it lies flat on the water.

5.      Then GENTLY drop a dry paperclip flat onto the tissue paper (try not to touch the water or the tissue paper).

6.      Use the eraser end of the pencil to carefully poke the tissue (not the paper clip) until the tissue sinks. (Slowly and strategically make sure the tissue paper is sinking and stays down. Though, you may take the tissue paper out of the water if it rises again.)

7.      With some luck, the tissue paper will sink and leave the paper clip “floating”!

8.      Try using a different size or shape of paper clip and make it “float”.

9.      Alternative way to make a paperclip “float”: Try using a bent paper clip to lower another paperclip into the water so that it is flat against the water.

10.  Have fun!

 Observe

How many paper clips can the water hold “afloat”?

Does the shape of the paper clip affect its “floating” ability?

Ask: How is it possible for a paperclip to float?

Alternative Way to Make It Float

Go to: https://sciencebob.com/make-a-paperclip-float/

This shows you how to lower the paperclip into the water by using another paperclip.

You can let the students all try this alternative way for a while before moving on to explaining why the experiment works.

Explain

Paper clips are NOT buoyant, but they do “float”.

How is that possible?

With a little thing we scientists call SURFACE TENSION.

–          Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in the floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects (e.g. water striders) to run on the water surface. This property is caused by cohesion of similar molecules, and is responsible for many of the behaviors of liquids.

–          Basically it means that there is a sort of skin on the surface of water where the water molecules hold on tight together. If the conditions are right, they can hold tight enough to support your paper clip. The paperclip is not truly floating; it is being held up by the surface tension.

 Fun Facts!

–          Tacks and pins can be held up on water by surface tension too!

–          Many insects, such as water striders, use surface tension to walk across the surface of streams or lakes.

–          Adding soap to the water will make the paper clips fall into the water and no more paper clips will be held up by surface tension.

–          Water has a surface tension of 72.8 dynes/cm, while mercury has a surface tension of 465 dynes/cm.

Other Examples of Surface Tension

–          Spiders, leaves on water, and water droplets on leaves, tables, and pennies.

 Ask: Does anyone have any other questions? (Before you move onto the closure.

 Learning Closure:                                           Time: 5 mins

 Review Questions

  1. What is Buoyancy?
  2. What is Buoyant Force?
  3. Do Paper Clips Float?
  4. How are they held up?
  5. What is Surface Tension?

Ask: What was your favorite part of this lesson?

 Get the students to hand in their worksheets to you at the end of the lesson.

Materials/Equipment:

–          “Experiment: Do Paper Clips Float?” PowerPoint.

–          POE Experiment Trifold Board on Surface Tension.

–          Package of paper clips.

–          Five bowls filled with water.

–          Small pieces of square tissue paper.

–          Pencils with erasers.

–          Bottle of dish soap.

 Management Strategies:

–          Explain to the students that it is important to be actively listening to instructions and following them in class.

–          If the students are too loud, get their attention by saying, “If you can hear me clap once”. Repeat the pattern until they are all quiet. Then continue with the lesson.

–          Ask for respect and their attention if students are too loud. Wait until they settle down.

–          While students are working in groups, walk around to make sure they are on task, use positive reinforcement, and answer any questions they may have.

 Safety Considerations:

–          Make sure the students are aware of their personal space and the others around them.

–          Make sure students are not poking themselves or other students with the paper clips.

 Possible Adaptations/ Differentiation:

–          There will be visual and auditory learning in the PowerPoint presentation and YouTube videos.

–          The videos are helpful for the visual and auditory learners.

–          The instructions for the experiment will be on the projected screen, the trifold board, and on pieces of paper in front of every group.