Cabbage Juice Lab

Today my 5th graders learned how to use red and blue litmus paper, as well as use cabbage juice as an indicator.  In the classroom, I had 6 solutions for them to test.  They could test the solutions in any order they wanted.  The solutions were: tap water, salt water, baking soda, Comet cleanser, vinegar, and a freshly squeezed lime. The only solution they had to be careful with was the Comet cleanser, everything else was harmless.

Each lab tray had the following set up (1 tray had supplies for 4 people to share, but they worked in pairs):

• One 125 mL flask of cabbage juice with a pipette
• red litmus paper vial
• blue litmus paper vial
• 12 clear plastic cups
• 1 large paper/coffee cup for used pH paper 

On the side of the classroom, I had the 6 containers of solutions with a pipette in each solution.  I used small take out containers I had at home. I have a habit of saving all types of plastic containers instead of throwing them out. As a teacher, they come in handy! I was able to set some stuff up at home and just add water to make the solutions when I got to school.  The tops were pretty secure so it was easy to transport.

To test the solutions, they only needed 3-4 pipettes full of each item placed into their cups. Back at their table, they tested using pH paper first, then added the cabbage juice. When using the cabbage juice, 3-4 pipettes full was plenty to observe the color change.

They were able to complete this activity within one class period. The red cabbage juice has a strong smell, which they were all to happy to comment about it! =)  I made the cabbage juice at home using half a head of red cabbage and boiling it for about 45 minutes to get a dark purple color.  Once it cooled, I placed it into an empty soda bottle and filled it up about 95%.  I added a small amount of rubbing alcohol to the bottle.  This helps to keep it fresher longer and stop it from getting rancid too quickly.  The rubbing alcohol does not change the properties of the cabbage juice or affect the pH. You can refrigerate it if you want to keep it longer as well.

Notebook:

pg. 116 – Cabbage Juice Lab

pg. 117 – Cabbage Juice Analysis

 

 

pH Scale Activity Sort

To introduce the pH scale, I created a partnered activity where students would place an example for each pH value according to 15 clues that were provided. Each student had a pH scale that I had printed on the color laser printer at school and had pre-cut for them. They glued it into their notebook, towards the edge of the page.

On card stock, I printed the same pH scale in color. I also printed out the 15 examples and cut them apart so that each one formed a rectangular tab.  To keep things organized, I labeled the plastic bag with the group #, and wrote that same group # on the back of each tab so that if they fell out or got mixed up, I could place the sets back together again.

To start the activity, I handed each person the colored pH scale to glue into their notebook.  When they were done, I had them close their notebooks and put them under the table so they had room to work. Then I handed out the cardstock version of the pH scale and one bag for each set of two students.  They removed the tabs from the bag , spread them out, and counted to make sure they had 15. We reviewed where the acids were (pH less than 7) and where the bases were (pH greater than 7). I explained how I was going to read clues and they had to place the tabs into the correct spots on the pH scale and, at the end, we’ll see how many they got right.  (It was like a game, not for a grade)

I read the clues and they worked with their partners to place the tabs where they thought they belonged. After the last clue, I gave them a minute to finish their pH scale and ask for repeated clues if they needed to.  Once everyone was ready for the answers,  I told them that if their tab was in the right spot, to leave it there, and if it was wrong, just slide it to the side. Do not make any changes. I revealed the tab that belonged to each pH value one at a time. At the end, we took a survey to see which partners had the most right. Some kids got 13/15, some had less than 10 correct.

We cleaned up  and took out our notebooks.  On the SmartBoard, I pulled up the answer key and we copied the answers next to each pH value.  Once their notebooks were up to date, I played the BrainPOP movie about the pH scale. I then handed out the activity page and they glued it into their notebooks. With a few minutes left in class, they started their hw.

The kids listened carefully to the clues, they collaborated with their partners, they used information from the pH scale to place their answers, and they wanted to do well. It was funny, when they got an answer right, they whispered ”yes!” and anticipated the next answer to see how many they would get correct.

Notebook:

pg. 114 – pH Scale Activity Sort

pg. 115 – BrainPOP pH scale activity

BrainPOP Movie: pH Scale

 

Acids & Bases Venn Diagram, Notes

Group SmartBoard Activity (25 minutes): For this activity, I broke it up into 5 parts.

Part 1: General Discussion about acids and bases, pH, and indicators.  Most 5th graders didn’t really have a lot of prior knowledge on this topic.

Part 2: Explained how they were going to watch a BrainPOP movie on acids and bases, and to listen for facts presented in the movie.  Using the list of facts on their handout, they were to write an “A” next to the facts that related to acids, and a “B” next to facts that related to Bases.

Part 3: Gave the students about 3-4 minutes to compare their fact lists with their lab partners. They may not have all the facts categorized, and that was ok.

Part 4: I explained how one person from each group was going to come up to the board and drag one fact into the Venn Diagram.  If they were correct, everyone wrote that fact into the Venn diagram on their handout.  Students had to choose who would go up for each turn, and what fact they would place. It was a good opportunity for collaboration and coming to a consensus. If the answer was incorrect, they had to drag the fact back to the bottom of the board.

Part 5: Go over all the answers, make sure that their notes reflected the  notes that were on the board.

The activity worked really well, the students were on task and it was a nice way to introduce new information in an interactive way.

I uploaded the notebook file to SMART Exchange, not sure if its fully functioning yet, here is the link.

Notebook/Links:

BrainPOP Movie – Acids and Bases

pg. 112 – Acids/Bases Venn Diagram

pg. 113 – BrainPOP – FYI – Gastric Acid