PR-0552UK Primary Science - Book 2

Mixing
Objective
• begin to investigate how
materials may be changed
by mixing
Working scientifically
• Questioning
• Observing
• Predicting
• Investigating and
experimenting
• Recording and
communicating
Designing and making
• Exploring
• Making
Background information
Mixing is the combination of two
substances.
Red, yellow and blue are called
primary colours and form the
basis of all other colours. Every
other colour can be produced by
mixing different combinations of
these colours. For example; red
+ yellow = orange; red + blue =
purple; yellow + blue = green.
Dissolving occurs when two
substances, like salt and water,
combine completely. Substances
generally dissolve faster and
more effectively in hot water
compared to cooler water.
Before the lesson
Materials needed
• White cartridge paper, primary colour tempera paints, palettes for mixing colours,
paintbrushes, water (in containers), paint shirts for pupils.
• Salt, coffee, flour, custard powder, glass jars, cold water, hot water, kettle for
heating water, spoons, teaspoons, oven mitts.
Preparation
• Set up suitable areas and stations for pupils to work in small groups to experiment
with paints.
• Set up the mixing of substances with hot and cold water as a demonstration at the
front of the class.
Note: This lesson on mixing can be conducted over two lessons.
The lesson
Stimulus
• Allow the pupils to observe the colour of objects inside and outside the classroom.
List the objects and colours on the whiteboard. Discuss.
What to do
• Give pupils a sheet of cartridge paper with their name on the back. Fold it in half.
Place small ‘blobs’ of red, blue and yellow paint along the centre fold (not too far
apart). Have pupils gently rub the sides of their hands from the fold outwards
to the paper edges. This should move the paint into patterns. (Be careful not to
let it ooze out the edges.) When finished, carefully open the paper to reveal a
symmetrical pattern. What colours can they see? How are they different from the
three primary colours they started with? How do they think the new colours were
made? Put patterns aside to dry.
• Using another sheet of paper, allow pupils to experiment using blue, yellow and
red paints to make new colours. Mix blue and yellow, blue and red and yellow and
red. Discuss results.
• To observe safety precautions, organise the Question 2 experiment so it is a
demonstration at the front of the classroom.
• Pupils can help spooning the four different substances into two jars each.
• Pupils can come to the front of the class to help pour the cold water into the first
set of jars. Pupils can help to stir. Pupils decide if the substance mixes easily or not
easily.
• The teacher pours hot water into the jars. Ask pupils to come and help mix, while
the teacher is still holding the jar with an oven mitt. Decide once again if the
substances mix easily or not.
• Pupils complete the table and decided if substances mix more easily (dissolve) when
mixed with hot water than with cold.
Viewing Sample
Materials and change ~ Activity 3
After the lesson
Answers
1. (a) Teacher check
(b) blue + yellow = green
blue + red = purple
red + yellow = orange
2. Answers will vary
3. Hot water
Additional activities
• Try mixing other substances in hot and cold water. The pupils predict what will
happen for each and test their ideas.
94 PRIMARY SCIENCE ~ Prim-Ed Publishing ~ www.prim-ed.com