Who are the teacher's lunch?
Students will need the worksheet for the activity
Equipment
Per group (recommended group size 3)
Each class will need at least 1 (we recommend 2) locked box with a 3 digit number padlock. A toolbox works well, but a cheaper version would be a cardboard box with a rope chain through some holes securing the box shut using the padlock. Number combination padlocks can be purchased from hardware stores such as Bunnings
Inside the box you will need a picture of a mouse (as this is the culprit that has eaten the teacher's cheese sandwich)
Each group will need:
Bicarb soda (approx. 2 teaspoons)
Water (approx 10ml)
Turmeric powder (approx ΒΌ teaspoon per group making the mixture)
Hand sanitizer (approx. 5ml per group)
Cotton tips for mixing and for writing with the solution
Small plastic medicine cups/shot cups to hold solutions (or small beakers if access to lab supplies). They will need one cup for each household solution being tested and an additional 2 cups per group to make the invisible ink and tumeric mixes in. *Note we recommend small medicine cups to reduce wastage of solutions.
Optional -absorbent sheets (puppy training pads) if doing this activity in a carpeted room, this reduces the chance of spills to the floor or staining to the tables.
Pool pH strips are available in the supermarket or at Bunnings. 6-8 strips per group depending on how many household solutions you want to test.
Alternatively you can use cabbage indicator by boiling up some red cabbage and adding some of the mixture to the solutions. The colour of the cabbage solution will change in the presence of acids or bases. Red, pink, purple are acidic colours, blue green yellow are basic colours.
Variety of kitchen liquids to test pH, in small labelled medicine cups, suggestions include milk, fruit juice such as orange juice, lemon juice, dishwashing liquid, soap solution, baking soda solution, hand sanitizer.
Preparation (moderate preparation is needed)
Prior to the day
This activity requires Code Cards to be made. This is simply a piece of paper with the 3 digit padlock code numbers written on it with invisible ink (baking soda and water paste) and "?" visibly written on it, this is so students know which side of the paper to test. The three digits need to be correct numbers for the code but not in the correct sequence.
eg. if the padlock code is 314, the code cards will have 431 or 341 etc written on them using the bicarb and water paste.
We recommend having sets (hand sanitiser, bicarb soda, turmeric, water, 2 medicine cups and 2 cotton tips) for the groups pre made for easier distribution on the day.
On the day
Distribute the bicarb soda, water, turmeric, hand sanitiser, cotton tips and medicine cups to the groups
Only when the students have made their invisible ink, turmeric solutions and unlocked the security footage should the household solutions and pool strips (or cabbage indicator solution) be supplied to the groups.
Additional Information
If running this activity in a standard classroom it is recommended to use a absorbent sheets (puppy training pads work well) to minimise spills.
Turmeric can stain items such as tables