Rainbow Jelly

Purpose

In this unit students work with teaspoons, tablespoons and fractions of a cup to make their own rainbow jelly, converting between units of volume as required.

Achievement Objectives
GM2-1: Create and use appropriate units and devices to measure length, area, volume and capacity, weight (mass), turn (angle), temperature, and time.
Specific Learning Outcomes
• Recognise the need for a standard unit of volume.
• Measure volume using teaspoons and table spoons.
• Convert between units of volume: teaspoons, tablespoons, half and quarter cups.
Description of Mathematics

This unit introduces students to units of volume smaller than a cup. The base units for these measurements are:

1 teaspoon = 5 mL
1 tablespoon = 15 mL
1 cup = 250 mL
1/2 cup = 125 mL

The learning opportunities in this unit can be differentiated by providing or removing support to students and varying the task requirements.  Ways to support students include:

• Support children by frontloading so they can see the connections and comparisons between a teaspoon (5mL), a tablespoon (15mL), a cup (250mL) and 1/2 cup (125mL). An example may be to ask, ‘How much bigger is the volume of a cup compared to a teaspoon if the cup is 250mL and the teaspoon is 5mL?’.
• Scaffold the children by giving them a task which will elicit free discussion in groups. An activity is to partly fill different shaped bottles and ask the children to order them according to the volume from the smallest to largest measure. Have plastic jugs with volume markings to check their estimations.
• Adapt the activity to use numeracy cubes instead of water if they have a suitable container. The different coloured layers can be seen which water wouldn’t show.

The context for this unit can be adapted to suit the interests and experiences of your students. For example:

• Investigate celebrations children may have in their homes where jelly is part of the dessert menu. Some examples are tangi, birthday parties, Christmas Day
Required Resource Materials
• Water, bowls and spoons to mix jelly
• Coloured jelly, up to 6 colours (the more colours used, the more calculations and conversions required)
• A variety of clear plastic cups, some with parallel sides and some with sloping sides, enough for at least one cup for each student.
• Measuring cylinders, small enough to enable measurements of 5ml up to one cup
• Metric measuring spoons and cups: teaspoons, tablespoons, cups
• Copymaster 1
• Copymaster 2
• Copymaster 3
• Copymaster 4
Activity

Before starting this unit discuss with children what is meant by the terms volume and capacity and what measurement they will be using for volume. Capacity is a measure of how much the container can hold whereas the volume is the measure of the amount of space that a 3-dimensional object occupies. The measurement for volume in this unit is mL (millilitres). All copymasters will need to be carefully introduced so children will be confident when using them.

Session 1

Rainbow jellies are individual cups of jelly, striped different colours like a rainbow.

1. Introduce students to the topic of rainbow jelly and check that all students know what they are.
Ideally, bring in one that you have made at home and ask students how they think it has been made.
2. Describe how the layers need to be made one at a time, being left to set between each layer.
3. Explain that this week they are going to work in groups to plan and make their own rainbow jelly.
4. Divide students into groups and give out three different shaped plastic containers to each group, at least one with parallel sides.
5. Have students experiment with measuring spoons and water in their cups to investigate the effects of the same volume in the different shaped containers.
6. Note that the shape of the cup will affect the way the final jelly looks. For example, if the cup has parallel sides and equal volumes of jelly are used for all colours the stripes will be the same height. Encourage students to investigate this and discuss their findings.

How could we make the stripes of jelly wider?
How could we make the stripes of jelly thinner?
How could you make all the colours the same height?

The task of making the stripes even will be more complicated in containers where the sides are not parallel.

Exploring

Over the next three sessions have each group of students complete plans for several different jellies, working with a different container each session.
Session 2: container with parallel sides
Session 3: container with sloping sides
Session 4: unusual shaped container, encourage students to bring a container from home for this purpose

During each session students can use water to fill containers to different levels as they plan designs for their jellies. They may choose stripes of the same depth, alternating thick and thin stripes, stripes that get progressively narrower. The plans they make need to specify the colours and volumes for each stripe alongside a sketch of the design.

Each different plan can be recorded on Copymaster 1.

As different plans are drawn up share these with the class and discuss the volumes of jelly used. Encourage conversion between teaspoons, tablespoons and cups.

How many tablespoons of red jelly have you used?
How many teaspoons would that be? How much of a cup?
Which colour have you used most of? Which colour have you used least of?
How much more red than yellow have you used?

Once planning is complete get the students to choose which of their plans they will make. Ask them to calculate how many packets of each colour jelly they will need if there are 8 people at the party. How many for 20 people?

Copymaster 2 can be used to guide and record these calculations.

Reflecting

Groups of students make their jellies. It would be simplest to mix the jelly required in bulk rather than have each group mix each colour individually. Note that the hot water needed could present a safety issue. To overcome this a small amount of boiling water could be used to dissolve the crystals first, then  cold water added before students use the jelly.

Once all the groups have their jellies complete and they have set, get students to estimate the volume of each colour jelly used in the different designs. Their estimates can then be compared to the actual volumes used. Copymaster 3 can be used for this.