Series: Ideas at Work

# Valentine’s Day Math Can Spark a Love of Symmetry

Cutting paper hearts for Valentine’s Day math fun is a common, early experience with symmetry for many young children. What joy to open a folded paper and discover a heart with two identical sides!

A shape has reflectional symmetry (also called line or mirror symmetry) if there is a line going through it that divides it into two halves, which are mirror images of each other. Folding a piece of paper creates this line, or axis of symmetry, and any shape cut along the fold will be reflected on the other side.

Have plenty of red paper on hand? Allowing children to explore where to fold and how to cut valentine hearts on their own leads to many discoveries. If the axis you fold at is not in the right place, the two halves aren’t identical at all.

Children are naturally curious about symmetry, so here are some more ways to explore symmetry that your children will love.

## Exploring with Mirrors

Provide children with cards showing geometric shapes, letters, and numerals and small mirrors. Allow children time to become familiar with ideas of symmetry and reflection. Then ask questions such as, “When you put the mirror there, does the shape look the same on both sides or different?” or “Can you find a place to put the mirror so you still have a letter H? or a number 3?

## Exploring with Blocks

Children naturally create block designs and structures with symmetry. As they add a block to one side, they add a block to the other to maintain balance and create a pleasing harmony of shape and form. You can nurture this interest by providing photographs of famous buildings and helping children notice their symmetrical features (those of us in Chicago are partial to the John Hancock Center). Can they replicate these famous buildings in the block corner?

Adding mirrors to play with pattern blocks invites more investigations with symmetry.

## Exploring with Books

For books that can extend thinking about shapes and their attributes, check out When a Line Bends… A Shape Begins by Rhonda Gowler Greene or Color Farm by Lois Ehlert. Both have a heart or two in them but include many other shapes to explore as well.

Geometry More

### Common Core Alignment

Operations and Algebraic Thinking More

Source: Erikson Institute • Copyright: Erikson Institute • Content ID: Not specified

# Algebraic Thinking with Shoes

Cindy Collado and her preschool class at Stock School were involved in a shoe project that incorporated many math concepts through a variety of activities over the course of two months. The class started by taking a good look at their shoes and then talking and thinking about what they saw.

# Control Your Math Fate, Estimate!

Ellen Stoll Walsh's book Mouse Count can be used in the classroom to cover such broad-ranging topics as data analysis, number sense, and number and operations. Key concepts such as estimation can be explored and investigated.

# Down with Naked Numbers

All kinds of confusion can result when children are asked to rattle off the numbers from 1 to 10 or 20 or higher without actually counting something. In our learning labs and activities we are working to help teachers find ways to avoid “Naked Numbers

## What do you think?

#### Carol Huntsinger

February 10, 2018 at 11:51am

Children do need to learn the sequence of number names–rote counting. They also need to learn one-to-one correspondence. Putting those skills together produces meaningful or rational counting. I believe there is a place for rote counting, which parents often do with their children. We need to explain to parents the difference between rote counting and rational counting, and of course, we need to do both in the classroom. The heading, “Down with Naked Numbers,” is misleading.