Monster Under the Bed
Julie Levine
January 25, 2012
Monster under the Bed
Teacher Kit
Ages 7-9
Time: 25-30 minutes
Summary
For this lesson, students will have to un-code “secret messages” from their next-door neighbor who is a “mad scientist” to figure out what is making strange noises under the bed.
The kids’ neighbor dropped off a box before the children woke up with a stack of seemingly blank pages of paper along with a bottle of grape juice, a crayon, a bottle of window cleaner, and a mirror. These various items are what is needed to decode to messages. The message will be made with:
1st note: ½ baking soda and ½ water—revealed with purple grape juice
2nd note: lemon juice and salt—revealed with a crayon
3rd note: this note is written backwards—revealed when the note is placed in front of a mirror.
4th note: goldenrod color changing paper and gold crayon--Revealed with window cleaner
The messages combined willsay: “Hey guys! I can’t find my new puppy! She likes to hide under beds. Have you seen her?”
The students should then deduce that their neighbor’s dog is under his or her bed.
If there is extra time, the students will be allowed to write secret messages to their parents or friends (they will have to take them home because they will need time to dry).They can choose the station with the type of message they liked the best and create their own message. They canbring the messages home to dry and reveal.
Modifications:
Older Children (9-12):This experiment can also be modified for older children by using the same recipes for secret messages and having a few that add up to solve a mystery but changing the story. Focusing more on how chemicals can change when they are exposed to other chemicals or temperatures can also modify the lesson. After observing the goldenrod color changing paper, students can work withpH strips (A-980 Alkacid Test Paper) to test pH along with the secret messages. The pH strips are made of a chemical that changes color based on the acidity of the solutions they are exposed to just like the goldenrod paper.
Depending on the age group, the activity could be easily incorporated into lessons around different holidays. For example for children ages 8-12:
One Halloween night Mr. and Mrs. Chemistry went out to a nice dinner. After a nice evening out, they came home to find that all of their Halloween candy had been stolen! The Halloween Hooligan had struck again! The Halloween Hooligan had been stealing candy from all of the houses in the neighborhood leaving mysterious blank sheets of paper on the front steps of the houses he stole from. Mr. and Mrs. Chemistry’s neighbors had thrown out the papers and bought new candy, but Mr. and Mrs. Chemistry wanted to figure out who was behind all of this candy stealing. The two of them realized the blank sheets of paper probably held secret messages waiting to be revealed. Can you help Mr. and Mrs. Chemistry reveal the messages and figure out who the Halloween Hooligan is!
The messages can reveal, “Hi Mr. and Mrs. Chemistry. This is Jimmy, the dentist’s son! My parents won’t let me have any of my own candy because they say it will rot my teeth, so I am stealing everyone else’s!”
A similar idea can be used around the holiday season with missing toys. This lesson is very easily modified to fit different themes.
Science Behind the Messages:
- 1.The baking soda and grape juice reaction can be used to demonstrate that chemical reactions can cause a color change. When the baking soda interacts with the grape juice, a color change occurs, revealing the message.
- 2. The lemon juice makes the salt stick to the page creating a texture. When students run the crayon on the salty words, more colored wax gets stuck there, showing the words. This can be used to demonstrate the idea of friction.
- 3. A mirror displays an object as directly opposite, “a mirror image.”
- 4.The Goldenrod color changing paper is made of an acid-base indicator, and when the paper comes in contact with either a basic or acidic solution, it turns bright red. The ammonia in window cleaner makes the solution basic, so the paper turns red as the solution interacts with the paper. The wax from the crayons protects the area where words were written. This could be used to lead into a unit on acids and bases and red-ox reactions or can be another example of chemical color changes.
Teaching Objectives:
- **Maine Learning Results: Inquiry and Problem Solving
Materials:
- Baking soda- enough to create the messages (a few table spoons)
- Water-enough to create the messages (a few table spoons)
- Purple grape juice- enough to be used as paint to reveal the messages (about one juice box per 10 students)
- Lemon juice- enough to write messages
- Salt- enough for pouring over the lemon messages
- Dark crayon- each student revealing the lemon juice messages needs a crayon
- Pen- to write the backwards mirror message
- Goldenrod color changing paper- one piece per group (can be cut into smaller pieces to save)
- Gold or yellow crayon- Teacher needs this to write messages. If students want to make their secret messages, more of this crayon will be needed.
Preparation:
Teacher would divide class up into four groups. Each group will be at one station at a time and rotate until every student has been at each station. At each station there will be a direction sheet explaining how to reveal the messages.
Teacher would pass out attached worksheet to students.
Station 1: Message 1: “Hey guys! I”
This message should be written with a ½ baking soda and ½ water mixture. It is important to make sure the solution is very well mixed before using it to write.
Direction Sheet: Brush the grape juice over the paper to reveal the secret message.
There should be cups with grape juice and paintbrushes at this station.
Station 2: Message 2: “can’t find my new puppy!”
The message should be prepared with lemon juice and then salt poured over it while the lemon juice is still wet.
Direction sheet: Color over the page to reveal the secret message.
There will need to be crayons at this station.
Station 3: Message 3: “She likes to hide”
This note will have to be written back wards.
Direction sheet: Use the mirror to reveal the secret message.
There will need to be hand mirrors at this station.
Station 4: Message 4: “under beds. Have you seen her?”
This station should have the goldenrod color changing paper written on with golden crayon.
Direction sheet: Use the window cleaner to reveal the secret message.
There will need to be spray bottles of window cleaner at this table. Dixie cups of window cleaner and paint brushes would also work here.
**I recommend covering this table with paper towels or at least have a dry cloth on hand for excess liquid.
Clean Up:
This will involve wiping down the counter where the window cleaner was sprayed as well as where the grape juice may have spilled. Crayons and mirrors will have to be collected. There is no chemical that would need special cleaning equipment in this lesson. The goldenrod messages can be used again for the same experiment if they are allowed to dry.
Reference:
Invisible Inks, January 6, 2012.
Goldenrod Paper can be ordered from Flinn Scientific Inc.
Direction Sheet: These can be cut out and placed at each of the stations with the messages. To make the task more challenging, students could be provided with various methods of revealing messages. They would have to experiment to determine which method works best.
Brush the grape juice over the paper to reveal the message.
Color over the page to reveal the secret message.
Use the mirror to reveal the secret message.
Spray the window cleaner on the paper to reveal the secret message.
Student Worksheet
Name______
There’s a monster under the bed!
Tommy and Katie just got home from school when they hear something moving around in their bedroom! At first, the two are scared, but then they remember that their new next-door neighbor is a MAD SCIENTIST. They assume that the noises are a robot or something crazy and fun that he has created for them to play with.
They go upstairs looking for their new toy, but can’t find a robot anywhere. They go back downstairs and see a box with all sorts of silly equipment in it. The box is from Dunkin Donuts, so the kids know it must have come from their MAD SCIENTIST neighbor because he eats so many donuts every day.
Inside the box are secret messages! Can you use the equipment in the box to reveal the secret messages and figure out what is making all of the noises coming from upstairs?
On the lines provided, write down each of the messages you reveal.
Message 1: ______
Message 2:______
Message 3:______
Message 4:______
Now read out loud all of the secret messages combined. What is the noise under the bed? How do you know?
______
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