Part of Unit: Chemistry of Life
Lesson Plan Overview / Details
Students learn about hydrogen bonds and why they are the "glue" that holds water molecules together. Students then apply that same principle to the concepts of cohesion and adhesion. Surface tension of water is also examined and demonstrated with an engaging group activity. Lastly, capillary action is discussed as it relates to these concepts.
- Lesson Time
- 2 Hours
California Career and Technical Education Standards
- ANR.C.C11.2 Understand plant growth requirements.
- ANR.FS.11.0 Demonstration and Application
- ANR.FS.9.6 Understand leadership, cooperation, collaboration, and effective decision-making...
California Academic Content Standards (Reinforced)
- ELA.11-12.R.VCD.1.2 Apply knowledge of Greek, Latin, and Anglo-Saxon roots and affixes to draw infer...2
- ELA.9-10.LS.C.1.1 Formulate judgments about the ideas under discussion and support those judgments...
- ELA.9-10.R.CAGT.2.5 Extend ideas presented in primary or secondary sources through original analysis...3
- ELA.9-10.W.RT.1.5 Synthesize information from multiple sources and identify complexities and discr...12
Objectives and Goals
- Students will learn about hydrogen bonds and their ability to connect water molecules.
- Students will be able to compare and contrast "adhesion" and "cohesion".
- Students will be able to explain how adhesion and cohesion impact the agriculture industry.
- Students will describe the concept of surface tension and explain why it occurs.
- Students will participate in an activity that demonstrates surface tension to increase their understanding of the concept.
- Students will explain the importance of capillary action in plants and animals.
bubbles (with bubble blowing wands), 2 packs of bubble gum (optional), drinking straws, red coffee stirrers, plastic cups or beakers, Sharpie marker
Activities in this Lesson
- Bubble Mania! - Hooks / Set
Before the class period starts, place about 10 bottles of store bought bubbles on random desks throughout the classroom. Then, take a bottle and go outside the classroom door to blow bubbles into the air. As students arrive to class, they won't understand what is going on. They will start asking a ton of questions. Instead of answering, instruct them to go inside, grab a bottle of bubbles and join you outside. As they come outside, have them form a "bubble tunnel" (two rows of students blowing bubbles with a walkway in between for other students to walk through).
CAUTION: This activity can also be done inside the classroom . . . however, the large amount of bubbles landing on the floor can cause an incredibly slippery and dangerous surface. I highly recommend doing this outside if possible!
After all students have arrived to class through the bubble tunnel, I have them pair up with someone that has a bottle of bubbles in their hands. They are given 3 minutes to blow the largest bubble that they can possibly blow. (During this time, I play " I'm Forever Blowing Bubbles" by 4-2-4 from the Anthems - Football album to add interest to the activity.)
Once the song ends, I ask the class to raise their hands if they were able to blow a bubble that was at least 1/2 inch in diameter. (Most students should have accomplished this.) Then, I ask who got a bubble that was at least 1 inch in diameter. (A few hands may go down but most should stay up.) I continue to ask this same question, with slight increases to the bubble size each time. The goal is to see how large of a bubble they were able to blow. (You can always spice it up at the end of the activity by awarding the winning pair a pack of bubble gum for their amazing bubble blowing efforts!)
Talk to the class about why it was that small bubbles were easy to get but large bubbles were very difficult to get and then keep (they pop easy). Lead students to making the connection that small bubbles had less surface area and didn't break as easily. Larger bubbles had a much larger surface area and tend to pop very easily due to the amount that they are stretched.
- I'm Forever Blowing Bubbles Song [ Download ]
- Why is Water Sticky? PowerPoint (part 1) - Lecture
This PowerPoint presentation defines hydrogen bonds, explains how they connect water molecules, and discusses cohesion and surface tension.
- Red Rover, Red Rover - Group Work
For this activity, take the class outside to a large, grassy area (I usually use our school's football field). You don't want to do this activity on concrete or dirt because it greatly increases the risk of a student getting hurt!
Once outside, tell the class that they were so well behaved during the notes that they get a special treat. Ask them to raise their hands if they ever played "Red Rover, Red Rover" in elementary school. (Most students will have some experience with this game.) Divide the class into two teams of equal size (try to mix males & females during the sorting process). Have each team member hold hands with one another and spread themselves out so that their arms are out and there is some tension between them.
CAUTION: Make sure that the students are only holding hands, not wrists! When they join at the wrists, the connection is a lot stronger (students who have played before will realize that and try to get an advantage over the other team). However, there is a big difference between playing this in elementary school and playing as a teenager. It is MUCH EASIER to get hurt if they are holding at the wrists!
The teams should line up so that they are facing each other. Make sure that there is a fair amount of distance between the two groups.
Each team should designate one person to serve as the "caller". This person will be responsible for calling the name of a student from the other team when the time comes. Once each team has a "caller", one team starts the game by singing the words "Red Rover, Red Rover send ____________ on over." (the caller would insert the name of a student) At that point, the student that was selected will leave their team and run towards the other team. The object is for them to try to break through the line of students. If they break through, the student returns to their home team. If they get caught, they have to stay on that team.
This continues back and forth in the same fashion. The team that has the most members at the end of the game WINS!! (you can adjust the time as needed but let them play for at least 10-15 minutes otherwise they won't have enough background information to draw conclusions from).
After the game is over, have students either form a circle and sit down on the grass (or return to the classroom if the grass is wet or the weather is bad). Ask the class what the purpose of playing Red Rover, Red Rover was. (They will mostly say that you are a cool teacher who gave them a break from learning.) Have them review the concepts that were taught in class earlier in the period (hydrogen bonds and surface tension). Ask them how the game helps to demonstrate those principles. What did they individually represent? Why were they joined at the hands? What determined if someone running towards the team would break through or get caught?
Guide students to the following conclusions:
- Each individual student in the line represented a WATER MOLECULE.
- The joined hands between two "water molecules" represented a HYDROGEN BOND.
- The entire line (team) represented SURFACE TENSION of water.
- If the person (object) had enough force & weight, it would break through the surface tension. If not, they would get caught.
- Why is Water Sticky? PowerPoint (part 2) - Lecture
This PowerPoint presentation defines adhesion and discusses how it influences capillary action. The importance of capillary action is described and evidence of this concept is shown using a variety of examples.
- Straw Showdown - Group Work
Have students pair up. Give each pair 4 items -- a regular drinking straw, a red coffee stirrer, a cup/beaker filled with water and a Sharpie marker. Have students put both the regular straw and the coffee stirrer into the cup. They should look carefully through the tubes and use the Sharpie marker to draw a line on the tube to mark the height of the water. Once students have done that, have them analyze their results. Why was there a difference in the height of the water between the regular straw and the coffee stirrer?
After some think time, ask different pairs to share. Which tube had a higher level of water in it? Was the result the same for every group? Why or why not? (lead students to the conclusion that diameter of the tube plays a huge role. If the diameter gets too large, the adhesive properties between the water and the side of the tube becomes less strong . . . causing the water not to rise as high.)
In agriculture, it is critically important that plants have incredibly small tubes within the xylem tissue that carry water and nutrients from the roots upwards into the body of the plant. If those tubes weren't small in diameter, plants would have a difficult time moving water and dissolved nutrients through their xylem tissue by capillary action. This same concept is also true in animals and humans. Our circulatory systems contain capillaries. Capillaries are incredibly small tubes that help move blood in our bodies. Since blood is mostly made of water, capillary action assists the pumping action of the heart to help keep blood moving in our blood vessels.
- Video: Why is Water Sticky? - Other
- Quiz -- Why is Water Sticky? [ Download ] At the end of the period, use this quiz as a quick method to assess student understanding of the main concepts taught.