Leaving a Colourful Trail
Overview
In order to help Hansel and Gretel find their way home, each camper will make their
own colourful chalk. This activity will help campers to understand what chemistry is, and
how to differentiate between physical and chemical properties.
Topic (s)
Grade Level
Cost (per camper)
Time (preparation and activity)
Complexity
Chemistry
Grade 1-2
$0.97
1 hour
Easy
Ontario Curriculum Links
Understanding Matter and Energy: Grade 2 – Properties of Liquids and Solids
Big Ideas
 Materials that exist as liquids and solids have specific properties
 Liquids and solids interact in different ways
Specific Expectations:
 investigate the properties of liquids (e.g., conduct experiments to compare the
rate at which different liquids flow) and solids (e.g., conduct experiments to find
out ways in which solids can be changed)
 investigate, through experimentation, interactions that occur as a result of mixing
and/or dissolving liquids and solids (e.g., salt and water, sand and water), liquids
and liquids (e.g., oil and water), and solids and solids (e.g., salt and sand
 Describe the properties of solids (e.g., they maintain their shape and cannot be
poured) and liquids (e.g., they take the shape of the container they are in and
can be poured)
 Describe some ways in which solids and liquids can be combined to make useful
substances (e.g., flour and water make paste; milk and chocolate powder make
chocolate milk)
 Identify conditions in which the states of liquids and solids remain constant (e.g.,
solids remain solid when broken; liquids remain liquid when poured) and
conditions that can cause their states to change (e.g., liquids may freeze when
the temperature drops; solids may melt when heated)
Theory and Background Information
Leaving a Colourful Trail
Chemistry is the study of matter, and how different kinds of matter interact in
chemical reactions. Matter is everything around us that has a volume and a mass,
or occupies space. Matter is made up of atoms, which are the building blocks of all
chemical compounds.
Matter can be distinguished by physical or chemical properties. Physical properties
are identifying features of matter that do not change its chemical composition. This
could include the shape or size of matter. Thus, a physical change does not alter
the molecular make up of matter and is often reversible. Chemical Properties are
directly related to the chemical nature of a substance, and help determine how it will
react with other substances. In a chemical change or a reaction, which is highly
difficult (and sometimes impossible) to reverse, a brand new substance is formed.
Indicators of a chemical change include, but are not limited to, the release of
energy in the form of heat or light, a colour change and the formation of gas bubbles.
Solubility is the ability of a substance to be dissolved. Solubility is a physical
property. A solute is the substance that gets dissolved, and can be a solid, liquid or
gas. A solvent is the fluid in which the solute gets dissolved. A solution is the
mixture that contains a solute evenly dispersed throughout the solvent.
The three states of matter are solid, liquid and gas. A change from one state of
matter to another is an example of a physical change. In a solid, the molecules
which compose the matter are packed very tightly together and have very little
energy to move around, which causes the object to retain its shape. The closer the
particles are, the harder the object is. In a liquid, the molecules are less close
together and have more energy and space to move around. These characteristics
are why a liquid will take on the shape of the container that holds it. Gas is a state of
matter which surrounds us. Its molecules are very far apart and are constantly
moving and bouncing at a high state of energy.
The change from a solid to a liquid is referred to as melting, while the change from
a liquid to a solid is called freezing. Liquid changes to a gas through evaporation
and a gas goes back to liquid form in condensation. The less commonly known
change from a gas to a solid, and the opposite, is called sublimation.
Materials
Per Group of 6:
 Pitcher of water
Leaving a Colourful Trail
 Plastic bowl
 Several measuring spoons (tbs, ½ tbs)
 Several markers
Per Camper:
 1 Popsicle stick
 1 Dixie cup
 1 Ziploc bag
Per Camp:
 Bag of Plaster of Paris
 Several colours of Tempera paint
 Saran wrap
Location


The activity will be prepared in St. Jerome’s, room 2009
Testing of the chalk will take place outside, likely at snack time, around the
outside of the building
Procedure
Preparation
1. Line Dixie cups with Saran wrap
2. Fill 4-5 pitchers of water
3. Fill 4-5 plastic bowls with Plaster of Paris
Introduction
1. Tell the class that today they will be making their own chalk using chemistry to
help Hansel and Gretel find their way home.
2. Ask campers if they know what chemistry is. Explain that chemistry is the study
of matter and the changes that happen to it.
a. Go around the room and pick up various objects, asking campers if those
objects are matter. Tell the class that matter includes everything around
us that takes up space.
3. Tell the campers that matter can come in three different states, solid, liquid or
gas.
a. Remind campers that in a solid, the particles are very close together and
don’t have much energy to move around.
b. Explain that in a liquid, the particles have more space, and that is why a
liquid will fill the shape of any container it is put in.
Leaving a Colourful Trail
c. Tell campers that in a gas, the particles move very fast and have tons of
room to spread out and float around.
i. Explain that the change from a liquid to a solid is called freezing,
from a solid to liquid is melting, from a liquid to gas is evaporation,
and from a solid to liquid is condensation. The changing states of
matter in water are a useful example here (i.e. ice, liquid water,
steam, condensation).
ii. Note: This will be review from the previous baking activity.
4. Explain that since matter is all around us, we have to have ways of dividing it into
different groups. Using a chart on the chalk board, indicate the difference
between physical and chemical properties.
a. To help campers understand the difference, ask them to help describe an
object, such as a bottle of water (and the water itself). Campers will likely
give descriptions of what the object looks like and how it feels. Explain that
these are the physical properties.
b. Use the examples of melting/boiling points of water, and the types of
molecules the substance is made up of to demonstrate how chemical
properties differ from physical properties.
Leaving a Colourful Trail
Activity
1. Divide the class into three groups of six, and one group of seven. Ensure that a
university leader accompanies the larger group, and that the junior leader floats
between all four groups.
2. To each group, hand out 1 popsicle stick and 1 Dixie cup per camper, a bowl
containing Plaster of Paris, a pitcher of water, measuring spoons and several
colours of Tempera paint.
3. Make sure that each camper writes their name on their cup before starting. Assist
as needed.
4. Have each camper measure 3 tablespoons of plaster into their Dixie cup.
5. With the assistance of a leader, get each camper to add 2 tablespoons of water
to their cup.
6. Using a popsicle stick, ensure that campers mix the plaster and water so that no
powder or lumps remain.
7. Allow each camper to select a colour of paint. Add the chosen colour to their cup
and again have them mix with a popsicle stick until the substance is a uniform
colour.
8. Cups can then be removed from the desk to dry.
9. Once the plaster chalk has hardened, get the campers to peel the cup off of their
chalk, and place any waste in the garbage.
10. Campers may then try out their chalk outside during snack time or on the
chalkboard if it’s raining.
11. Once campers have finished testing their creation, give them a Ziploc bag to take
the chalk home. Make sure that each bag is labelled with the campers’ names.
Activity Accommodations and Extensions
Accommodations
For campers with motor skills difficulties, a leader can help them measure and/or mix
their chalk (using hand over hand technique if applicable).
If a time constraint exists, leaders can mix a larger amount of plaster and water
altogether, and choose one colour for the class. Campers can also be asked to test their
chalk at home, rather than at camp.
Extensions
For campers who wish to learn more, extend the introduction to explain reactions,
indicators and solubility.
Campers can work together with their chalk to create a pictorial representation of what
they have learned.
Leaving a Colourful Trail
Safety Considerations
Make sure that campers do not place any materials in their mouths. After making and
playing with their chalk, have each child wash their hands.
Templates
See introduction
Resources
http://www.clickandlearn.org/gr9_sci/particle_theory.htm
http://www.enchantedlearning.com/crafts/plaster/chalk/