After 257 Mystery Seed of the Week posts, it seemed like it was time for a change. But what to do next?

The answer was inspired by a book, Seed to Seed: The Secret Life of Plants by Nicholas Harberd.

Seed to Seed is the journal of plant geneticist Nicholas Harberd from the year 2004. In it, he records his personal observations and discoveries. Because of his prominence in the field, in many ways it is also the story of the uncovering of the genetic control of plant growth.

Right in the first entry in the book, Harberd reveals that over the last few decades plant scientists have decided on a unifying method to help move the field of plant genetics forward more quickly. Instead of trying to examine a little of the genetics and development of many, many different plants, perhaps it would be more enlightening for everyone to study one plant thoroughly and assume that the other plants probably had the same or similar properties.

The plant they chose to investigate was thale-cress, Arabidopsis thaliana.

Arabis_thaliana_illustration(Public domain illustration of Arabidopsis thaliana by Johann Georg Sturm from Wikimedia)

Why did they select this small weedy plant? Arabidopsis thaliana is the lab rat of the plant world. It is small and it self-pollinates, so it can be grown easily in the lab. It completes its life cycle quickly, producing flowers within approximately three weeks and seeds in about six weeks. In addition, thale-cress has a small genome that has been completely sequenced, so geneticists can build on what is already known.

Where does this unifying idea take us?

Rather than moving randomly from plant species to plant species as we have been doing with Seed of the Week up to now, let's change gears.  Following in Nicholas Harberd's footsteps, let's learn more about plant science by delving deeply into the secrets of a single type of plant over the next few months. Who knows what we might find out!

What do you think of this plan? Would you like to join in the journey? What questions about plants would you like to answer?

Arizona's seasons are often out of sync, especially in the Sonoran Desert. When everyone else is shutting down and getting ready for fall and winter, our wildlife is gearing up. A few weeks ago, we featured some insect eggs. Now we have caterpillars and chrysalids galore.


Take this larva of a queen butterfly resting on a rush milkweed. It is taking advantage of the new growth the plants are putting out after recent rains.

queen-chrysalis-003Some of the faster developing larvae have already transformed into chrysalids. They will soon be adult queen butterflies.

skipper-on-cordiaThe skipper butterflies have already reached adulthood and are ready to lay eggs again.

Check out this post by Margarethe Brummermann who says there were 28 species of butterflies (as well as other insects) in Madera Canyon this week. She also posted an amazing video on Flickr.

 What insects did you see this week?


This week for STEM Friday we have physical science activities inspired by the new book:  The Kids' Book of Simple Machines: Cool Projects & Activities that Make Science Fun!by Kelly Doudna.

The Kids' Book of Simple Machines is the perfect hands-on science book for early elementary-aged children. It has concise explanations of the science of simple machines,  clear step-by-step instructions, and enticing colorful photographs of the projects. In addition, the background information in the different sections introduces children to famous scientists and inventors, from Archimedes to the Wright brothers.

The six simple machines covered are the lever, pulley, inclined plane, wedge, wheel and axle, and screw. After a brief introduction to each type in the front, the following chapters give more in-depth information, numerous examples of the different simple machines, and several activities and projects to explore the concepts more fully.

Whether you are teaching science in the classroom, after school, or at home, The Kids' Book of Simple Machines is a well-designed and useful resource. The young makers of the world are going to have hours of fun trying out the activities in this book.

Related Activities:

1. Archimedes Screw

One of the simple machines from the book is the screw.

Screws1_(PSF)(Public domain image from Wikimedia)

A screw is an inclined plane wrapped around some sort of central core. In addition to holding pieces of metal or wood together, screws can also be used to move objects. Propellers are types of screws that help move boats through water or airplanes through the air.

One of the earliest examples of a screw being used to move things was invented by the Greek scientist Archimedes. We all know that water moves down slope because of gravity. Archimedes figured out a way to move water against gravity using a device that now bears his name, the Archimedes screw.

Check out this video of a simple Archimedes screw made by a young girl:

Instructions for making an Archimedes screw may be found at:

2. Simple Machines Quiz

After reading this introduction to simple machines at Idaho Public Television,  figure out what kind or kinds of simple machines are illustrated here  (Public domain images are from Wikimedia).

Answers are at the bottom of the post.

A. What kind(s) of simple machine(s) are these scissors?


B. How about this wheelbarrow?


C. What kind of simple machine is an adze?


D. How about this press, which might be used to squeeze the juice out of apples?


Learn more with The Kids' Book of Simple Machines: Cool Projects & Activities that Make Science Fun!by Kelly Doudna

Age Range: 5 - 9 years
Grade Level: Kindergarten - 4
Paperback: 144 pages
Publisher: Mighty Media Kids (August 25, 2015)
ISBN-10: 1938063597
ISBN-13: 978-1938063596

Disclosure: The book was provided by the publisher for review purposes. Also, I am an affiliate with Amazon so I can provide you with cover images and links to more information about books and products. As you probably are aware, if you click through the highlighted title link and purchase a product, I will receive a very small commission, at no extra cost to you. Any proceeds help defray the costs of hosting and maintaining this website.

Come visit the STEM Friday blog each week to find more great Science, Technology, Engineering and Math books.


A. Scissors:  You are correct if you answered lever or wedge. Scissors are complex machines consisting of double levers and wedges (the blades).

B. Wheelbarrow:  Also a complex machine, a wheelbarrow combines a wheel/axle with a lever.

C. Adze:  The blade of the adze is a wedge.

D. Press:  The simple machine found in this press is a screw.

How did you do? If you'd like to learn more about simple machines, please let us know.