5 Easy Food Experiments #NationalScienceWeek2016

It’s #NationalScienceWeek2016! We’re passionate about food and education so we’ve researched five easy science experiments kids can do with food.  These experiments all use ingredients and materials found around the home. They are safe for kids (small children might need help with some materials like boiling water) and the environment. You don’t need to buy stuff and you can conduct these experiments in the classroom or  the home kitchen.  We hope your students and children have fun with science and enjoy learning about the world around them.

1.Dancing Raisins

Materials

#NationalScienceWeek2016
Image courtesy of http://buggyandbuddy.com/dancing-raisins-science-experiment-science-invitation-saturday/
  • small handful of raisins
  • 2 clear glasses
  • carbonated water

Method

  • Pour some carbonated water into a clear glass.
  • Add some raisins and watch what happens.

Questions to Spark Curiosity and Critical Thinking for #ScienceWeek2016

  • What do you think makes the raisins go up?
  • What do you think makes the raisins go down again?

The Science Behind It

Raisins are denser than the liquid in the soda water, so initially they sink to the bottom of the glass. The carbonated soft drink releases carbon dioxide bubbles. When these bubbles stick to the rough surface of a raisin, the raisin is lifted because of the increase in buoyancy. When the raisin reaches the surface, the bubbles pop, and the carbon dioxide gas escapes into the air. This causes the raisin to lose buoyancy and sink. This rising and sinking of the raisins continues until most of the carbon dioxide has escaped, and the soda water goes flat. Furthermore, with time the raisin gets soggy and becomes too heavy to rise to the surface.

2. Colourful Cabbage Leaves

Materials

#NationalScienceWeek2016
Image courtesy of http://www.icanteachmychild.com/ice-cream-in-a-bag/
  • Cabbage leaves (try wombok (chinese cabbage) or you can use white flowers
  • 4 x different food colours
  • Water
  • 4 x jars

Method

  • Add some water to each jar.
  • Next add a different coloured food dye to each jar (try 10 drops per jar to make sure the water is vibrant)
  • Then add a separate cabbage leaf/flower to each jar
  • Leave your cabbage/flowers over night to achieve the full effect of this experiment

Questions to Spark Curiosity and Critical Thinking for #ScienceWeek2016

#NationalScienceWeek2016
Image courtesy of http://www.icanteachmychild.com/ice-cream-in-a-bag/
  • Why did the leaves change colour?
  • How did the leaves change colour?

The Science Behind It

The leaves absorb water up through their stems.  As they do so, the coloured water also changes the colour of the leaves.

3. Ice Cream in a Bag

The best thing about this experiment is you can eat it afterwards! This experiment only makes a serving of ice cream.  You can double the recipe but no more otherwise it won’t work with the materials you have.

Materials

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Image courtesy of http://www.icanteachmychild.com/ice-cream-in-a-bag/
  • 2 x ziplock sandwich bags
  • 2 x ziplock large bags (approximately A4 size)
  • 1/2 cup milk
  • 1 tablespoon sugar
  • 1/2 teaspoon vanilla
  • 1/2 cup rock salt
  • winter gloves (to fit your student or child)
  • 2 cups of crushed ice

Method

  • Pour milk into one of your sandwich-sized ziplock bags.
  • Add 1 tablespoon sugar and 1/2 teaspoon of vanilla extract.
  • Get all of the air out and then seal the bag.
  • Place your filled bag into another sandwich-sized ziplock bag and seal.
  • Put your double-bag inside one A4 ziplock bag.
  • Add your ice and 1/2 cup of rock salt.
  • Place this bag inside another A4 ziplock bag (you will have 2 small bags and 1 large bag inside).
  • Ask the students to put their gloves on.
  • Ask the students to shake the bag.
  • Shake the bag for 15-20 minutes (you can pass it around the classroom or family).
  • Voila!  Ice cream is ready to be served!

Questions to Spark Curiosity and Critical Thinking for #ScienceWeek2016

  • How did the milk turn into ice cream?

The Science Behind It

The salt lowers the temperature at which ice freezes, or raises the temperature at which it melts (which is why it is used on roads in countries where it snows in winter).  Instead of melting at 0 degrees Celsius, the rock salt causes the ice to melt at a much lower temperature (depending on how much salt you add).  The more rock salt you use, the lower the temperature the ice will melt at.   This creates an environment that the ice cream mixture can freeze below the normal 0 degrees Celcius.  Then the salt/ice slush absorbs the heat from the milk mixture, lowering the temp of the milk and causing the cream to ‘ice’, creating the yummy ice cream texture!

4. Invisible Ink

Materials

#NationalScienceWeek2016
Image courtesy of: http://tinkerlab.com/invisible-ink-a-citrus-painting-experiment/
  • Lemon or lime juice
  • Paper
  • Paint brush or cotton bud
  • Iron or hairdryer

Method

  • Squeeze the juice into a bowl.
  • Paint the juice onto your paper with a paint brush or cotton bud.
  • Wait for the paper to dry.
  • Heat the paper with an iron or hair dryer (be careful that you don’t hold it there to long, as it could burn the paper).

Questions to Spark Curiosity and Critical Thinking for #ScienceWeek2016

  • Why was the juice invisible on the paper?
  • How did the invisible painting become visible?

The Science Behind It

The juice oxidises when heated (that is, the compounds that make up the juice lose some electrons therefore changing their chemical makeup), and this oxidation turns the compounds brown. Acids work well for this type of ink because they oxidise and change the chemical makeup of the paper, causing it to burn and char more easily.

Science on a Stick

Materials

#NationalScienceWeek2016
Image courtesy of: http://kitchenpantryscientist.com/science-on-a-stick-rock-candy/
  • 5 cups white granulated sugar
  • 2 cups water
  • paddle pop sticks
  • food colouring (4 different colours)
  • 4 clear jars

Method

  • Dip one end of the paddle pop sticks in water and then roll it in granulated white sugar. The sugar should cover 6-7 cm of the stick.
  • Let the stick dry completely (these are the seeds for the sugar crystal growth).
  • Boil 2 cups water
  • Add 5 cups sugar to the boiled water and stir until the sugar is dissolved as much as possible. It should look like syrup.
  • Leave the sugar syrup to cool and then pour into the jars.
  • Add food colouring and stir.
  • When coloured syrup is cold,  set the sugary end of the paddle pop stick into the syrup and let them sit for about a week.

Questions to Spark Curiosity and Critical Thinking for #ScienceWeek2016

#NationalScienceWeek
Image courtesy of: http://kitchenpantryscientist.com/science-on-a-stick-rock-candy/
  • Why did the crystals grow on the stick?

The Science Behind It

A supersaturated solution is one that is forced to hold more atoms in water (or another solution) than it normally would. Supersaturated solutions can be made using heat or pressure. Crystals start to form when a supersaturated solution encounters a “seed” atom or molecule, causing the other atoms to come out of the solution and attach to the seed. In this case, the seed molecules were the sugar molecules dried onto the sticks.

 

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