Parts of a Whole in a Circle

• Circle diameter: 21 cm
• Element mounting: magnetic base on the reverse side of every element
• Working surface: metal (magnetic) board
• Colouring: sectors of different fractions are coloured differently

Kit Contents:

The whole

• Solid circle, represents the whole (1) — 1 pc

Fraction sectors

• Sector 1/2, half of the circle — 2 pcs
• Sector 1/3, one third of the circle — 3 pcs
• Sector 1/4, one quarter of the circle — 4 pcs
• Sector 1/5, one fifth of the circle — 5 pcs
• Sector 1/6, one sixth of the circle — 6 pcs
• Sector 1/8, one eighth of the circle — 8 pcs
• Sector 1/12, one twelfth of the circle — 12 pcs

The sectors of each fraction make up a complete circle, so every group can be assembled into a full circle of the same diameter as the solid whole.

Product passport: ULABS-M017 (PDF)

Use

• Demonstration starts from the whole: the solid circle is attached to the board as the reference, and circles of 1/2, 1/3, 1/4, 1/5, 1/6, 1/8 and 1/12 sectors are assembled next to it.
• Because all assembled circles have the same diameter, the larger the denominator, the smaller the sector and the more sectors are needed to make the whole.
• Equivalent fractions are shown by overlaying sectors: two 1/4 sectors, three 1/6 sectors and six 1/12 sectors each cover one half.
• Addition and subtraction of fractions are shown by completing the circle to the whole and by removing sectors from an assembled circle.
• The same sectors are used to move on to decimal fractions and percentages: the filled part of the circle is the same quantity written as a common fraction, a decimal fraction or a percentage.

Preparation

• Sort the elements by fraction and assemble a full circle from each group — this also checks that the kit is complete: sectors of one fraction close the circle with no gap and no surplus.
• Check that the fraction marking is clear, the edges are even and the magnetic base is glued over the whole area, without peeling or blistering.
• Check the working surface: only a magnetic board holds the magnet, and chalk dust has to be wiped off, because a layer of dust weakens the attraction.

Safety

• Intended for general secondary education, for learners aged 10 and over (grade 5 and above), under the supervision of a teacher.
• Keep the magnetic sectors away from bank cards, electronic media, watches and other devices sensitive to magnetic fields.
• Do not let the sectors snap sharply onto the board or onto each other — the impact chips the magnetic layer off the sector base.
• Remove a sector from the board by sliding it sideways, not by pulling it off by the edge.
• Check that the kit is complete after every lesson: without one sector the corresponding fraction no longer makes up a full circle.

Maintenance and storage

• Wipe the sectors with a soft cloth slightly moistened with water and a neutral detergent, then dry immediately. Do not immerse them in water and do not use solvents.
• Check the magnetic base of each sector periodically and re-glue a base that has started to peel at the edge.
• Store the sectors flat in the supplied packaging, sorted by fraction, in a dry room away from heaters and direct sunlight; do not place heavy objects on a stack of sectors.
• Storage conditions: temperature +5 °C to +40 °C, relative humidity 60 %.

Compliance

• Complies with the general product safety requirements of European Union legislation. The product is not electrical or electronic equipment, so the WEEE marking does not apply to it.