How to Do a Math Magic Trick

Everyone knows magic tricks are fun, but not enough people realize that math can be as well. Whether you're teaching students or just having fun with your friends, these tricks will give them a good surprise.

Guessing Age and Shoe Size

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   Ask a volunteer to write down her age. Give her a piece of paper and instruct her not to show you what she's writing.

   • This trick won't work on someone 100 years old or above, but that's almost never a problem!
   • Have her multiply it by 5. Ask her to follow your instructions as you tell her what calculations to solve. Start by asking her to multiply her age by 5.

     • For example, if someone is 42 years old, she would write down 42 x 5 = 210.
     • Let her use a calculator if she'd prefer to.
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     Write a zero at the end of the answer. This is the same as multiplying by 10, but phrasing it this way makes it more difficult for the volunteer to follow the trick.

     • In our example, adding a zero to 210 makes 2100.
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     Add today's date. It doesn't actually matter what she adds here — we'll undo it later — but today's date is an easy small number to add. Mention the date aloud to make sure she knows it.

     • For example, if today is March 15th, the volunteer in our example would sum 2100 + 15 = 2115.
     • Tell her to ignore the month and year.
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     Double the answer. The volunteer should multiply her answer by two. (This is where a calculator comes in handy.)

     • 2115 x 2 = 4230.
     • Add the volunteer's shoe size. Ask the volunteer to write down her shoe size, and to round up if it's not a whole number. She should add this to her last answer.

       • If her shoe size is 7, she'll add 4230 + 7 = 4237.
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       Subtract twice today's date. It's best to calculate this in your head, then tell her to subtract the number you come up with.

       • For example, it's March 15th in our example, so multiply 15 x 2 = 30 in your head. Say "Subtract 30 from your answer" and the volunteer will calculate 4237 - 30 = 4207.
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       Reveal the magic. Tell her to read her answer out loud. The first part of the number is her age, and the last two digits are her shoe size.

7 Classroom Math Activities That Will Make Math Engaging and Fun

Fun, hands‑on math games are a great way to make early math concepts clear and keep your students engaged.

Introducing math games into the classroom is a great way to make learning fun, engaging and motivating for young learners.

And the best part about starting early (kindergarten to grade 2) is that it helps your students to develop a positive attitude toward math from an early age, setting them up for a successful academic future.

Here are some fun classroom math activities that will have your students begging to do more.

Math Bingo

This math game is sure to become a fast favorite with your students. You can choose whatever skill you want to review, such as addition, subtraction, or number sequencing. The game works just like regular bingo, except students have to solve math problems in order to know what number to mark off of their sheet.

To prepare, make a list of 25 math problems (e.g. 2+1, 3–0, or 2, 4, 6, _ ). Write the answers on the same sheet of paper.

Create your own 5x5 bingo cards or generate them online. At random, write the answers on the cards using the solutions from your list. There should be a bingo card for each student playing. You can laminate the cards to use for next time and have students place pennies or rocks to mark their answers.

Make a paper plate clock

Are your students learning to tell time this year? This hands‑on craft activity is a fantastic way to practice this important skill.

Start with a paper plate and make a small hole at the center. Students should write the numbers in the correct places. Using colored paper, they can then cut the clock hands to the right size and secure them using a split pin from the center. You can even use a second plate (different color) for students to write the minutes. Glue the second plate to the bottom of the first so that it creates a rim.

Guess the weight

Children love playing guessing games, and when it comes to whether something is heavy or light, there can certainly be a few surprises in store for them.

Gather several items and spread them across a table. One at a time, ask students to guess the weight of each item and write their predictions in one column on a page (you can create a simple template for this too). Using kitchen scales, invite individual students to weigh each item and record the correct answers in a second column. You can also add a column in between and pass each item around the class, so students can guess the weight after holding each in their hand.

Hopscotch math

This game is a great way to get your students outside on a nice sunny day. Using a piece of chalk, draw a hopscotch grid on the pavement mimicking a calculator layout. Ask students to form a line and one by one, give them a simple operation (e.g. 2+3, 5–0). Students should take turns hopping on each element of the equation in the correct order, landing finally on the answer.

In another game, you can call out a number and ask students to hop on any equation that equals to that number. For a fun twist, ask students to hop on one leg for odd numbers, and two legs for even numbers.

Hopscotch math is a fun activity which helps students to practice simple operations.

Pizza fractions

Fractions can be tricky, so this activity can really help students to visualize key concepts. Create an instruction sheet with five different fractions on each (you can create several so different students get a different set). Students should create a pizza (using construction paper, or even the inside of an empty pizza box) and decorate the toppings to represent each fraction.

For example, if they had a quarter (fourth), they should cover one-quarter of the pizza with a specific ingredient (e.g. mushrooms or pepperoni).

'Lengthy' scavenger hunt

Divide students into groups and give each group a list of measurements and a measuring tool (e.g. a ruler, tape, trundle wheel). Instruct students to find items that are exactly the length of what they have listed. For younger students who haven't yet been introduced to measurement, draw various lines on their sheet and ask them to find items that are exactly the same length.

Make sure you prepare items beforehand and place them in a safe and visible spot. This activity can be done outside or in the classroom.

Survey and graph

Ask each student to think of a question they’d like to survey their fellow classmates on. For example, they might like to ask their classmates what their favorite animal is out of a dog, monkey, pig, or chicken. Give students time to walk around the classroom quizzing each other and recording their data.

Once students have collected enough data, ask them to represent their results by building a bar graph using linking cubes, blocks, or Legos. They can use sticky notes or bits of paper to create labels above each bar. Take a photo of each student's graph, which you can later print out to create a class collage to display.

Symmetry (geometry)

A drawing of a butterfly with bilateral symmetry, with left and right sides as mirror images of each other.

A geometric object has symmetry if there is an "operation" or "transformation" (such as an isometry or affine map) that maps the figure/object onto itself; i.e., it is said that the object has an invariance under the transform. For instance, a circle rotated about its center will have the same shape and size as the original circle—all points before and after the transform would be indistinguishable. A circle is said to be symmetric under rotation or to have rotational symmetry. If the isometry is the reflection of a plane figure, the figure is said to have reflectional symmetry or line symmetry; moreover, it is possible for a figure/object to have more than one line of symmetry.

The types of symmetries that are possible for a geometric object depend on the set of geometric transforms available, and on what object properties should remain unchanged after a transform. Because the composition of two transforms is also a transform and every transform has an inverse transform that undoes it, the set of transforms under which an object is symmetric form a mathematical group, the symmetry group of the object.

 

Patterns in nature

Natural patterns form as wind blows sand in the dunes of the Namib Desert. The crescent shaped dunes and the ripples on their surfaces repeat wherever there are suitable conditions.

Patterns of the veiled chameleon, Chamaeleo calyptratus, provide camouflage and signal mood as well as breeding condition.

Patterns in nature are visible regularities of form found in the natural world. These patterns recur in different contexts and can sometimes be modelled mathematically. Natural patterns include symmetries, trees, spirals, meanders, waves, foams, tessellations, cracks and stripes.^[1] Early Greek philosophers studied pattern, with Plato, Pythagoras and Empedocles attempting to explain order in nature. The modern understanding of visible patterns developed gradually over time.

In the 19th century, Belgian physicist Joseph Plateau examined soap films, leading him to formulate the concept of a minimal surface. German biologist and artist Ernst Haeckel painted hundreds of marine organisms to emphasise their symmetry. Scottish biologist D'Arcy Thompson pioneered the study of growth patterns in both plants and animals, showing that simple equations could explain spiral growth. In the 20th century, British mathematician Alan Turing predicted mechanisms of morphogenesis which give rise to patterns of spots and stripes. Hungarian biologist Aristid Lindenmayer and French American mathematician Benoît Mandelbrot showed how the mathematics of fractals could create plant growth patterns.

Mathematics, physics and chemistry can explain patterns in nature at different levels. Patterns in living things are explained by the biological processes of natural selection and sexual selection. Studies of pattern formation make use of computer models to simulate a wide range of patterns.