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Science Investigations

Week 12

This week there are 3 investigations for you to carry out. Two are for Rainbow celery and one is to make invisible ink. See if you can be a super scientist and don't forget to send your photographs to


Science Investigation-Rainbow celery

Have you ever seen a plant with red or blue leaves? Here's a clever way to make a stick of celery change colour. It will look like magic!

You will need:

sticks of celery with leaves

three small glasses

red and blue food colouring (or other colours)


kitchen scissors

Instructions for investigation 1:

  1. Trim the bottom of a stick of celery so that it is about 15 centimetres long. Leave the leaves on. 
  2. Pour water into one glass so it is a third full. Add a small amount of food colouring.
  3. Put the end of the celery into the liquid in the glass. Leave the glass in a safe place where it won't be moved.
  4. After one day, take the celery out of the water and cut across the base of the celery with scissors. You will see lines of colour rising up the stalk.

Instructions for investigation 2:

  1. Next put water in two glasses and add a small amount of food colouring (one red glass and one blue glass).
  2. Split another stick of celery and allow each part of the split stalk to stand in each of the glasses.                         
  3. Leave for a day and then take out of the water and you will have multi-coloured celery. Cut back the stalks to check.  


What has happened?

Plants need water, just like we do. They take up water through their roots. The water travels in little tubes, all the way through the stem to the leaves. if you put dye in the water, the coloured water will be carried to the leaves too. 


Now try this:

Put a flower with white petals in water with food colouring. Leave it overnight. What do you think will happen? What did happen? Can you explain why?


Invisible Ink

Write an invisible secret message that can't be seen and then use chemical reactions to make it appear! Follow the steps below to make your very own invisible ink. Could you send a secret message through the post to a friend or relative and ask them to send one back to you?  Pass a secret message to someone in your house too.

You will need:


lemon juice,

a small bowl,

a paintbrush or cotton bud

a warm radiator or hairdryer


  1. Squeeze the lemon juice into a small bowl.
  2. Get a piece of paper and think of a message.
  3. Dip your paintbrush or cotton bud in the juice and use it to write your secret message.
  4. Leave your paper to dry.
  5. To see the message  leave the paper on a hot radiator for a while or heat it with a hairdryer. Ta-da! The message will be revealed.


What happened?

Many materials, like lemon juice,  react when they are heated. This makes them change and sometimes change colour. The juice turns brown as it gets hotter. You can also see this happening when you cook some types of food, such as toast, cake and onions. 


Try this:

Some other materials can also work as invisible ink. Try apple juice, lemonade or white vinegar and investigate to see if they work as well. Which material worked the best as invisible ink?