physics classes

A Mind-Bending New Way of Looking at Big Ideas and Numbers

Dear Teacher, My interest in scale began when I was a boy, building model ships. As a teacher, I used a lot of activities related to models and scale to get children thinking about the sizes and relationships of big things. These exercises taught me just how powerful scales and modeling can be.

From ideas like this came my books If the World Were a Village, If America Were a Village and This Child, Every Child. They scale down big ideas and issues into something more digestible, more meaningful. Here are some activities to use with children to help them understand scale by playing with it and using their imaginations.

Try them and, most importantly, have fun, think imaginatively, ask students to create scales and time lines, and rely on rounding. And don’t worry — you can’t do it wrong. Start a Scale Collection Children are surrounded by objects that have been scaled down, such as dolls, toy cars and dinosaurs. Continue reading “A Mind-Bending New Way of Looking at Big Ideas and Numbers”

kids chemistry lesson fun

Chemistry Activity: Hide and Seek


The purpose is to develop students’ understanding of substances that dissolve in one solution and not in another solution.

Content Connections:

Properties of objects and materials, soluble and insoluble

Background Information:

Substances that are ionic compounds like table salt and salt substitute, will easily dissolve in water. Oil does not easily dissolve in water, but will dissolve more readily in an oily compound like a stain treatment stick or spray.

Watercolor paper, watercolors, paint brushes, wax crayon, wax candles, pieces of cloth


Before class write a message on a white piece of watercolor paper with a white crayon. Hold up the paper and ask the children, “I have a message from my best friend. Can anyone read this message?” Allow the children to briefly tell you what the message says. Wash the watercolor paper with watercolors.

The message appears. Ask the children to read the message now.“Why do you think the message appeared?”

Record the children’s initial ideas.

Ask the children questions like the following: Did you ever get in trouble for coloring on the wall with a crayon? How did you parents remove the crayon? Allow the children to briefly share their experiences.


Pass out white crayons. Allow the children to write secret messages on white watercolor paper. Then allow the children to paint over the message with watercolors so the message appears. Ask the children, “Do you think this is how I
wrote the message to my best friend?” Record the children’s initial ideas. Continue reading “Chemistry Activity: Hide and Seek”