Line Symmetry

Yesterday we learned a new attribute/property that can be used to identify some plane figures.  Symmetric shapes have one or more lines of symmetry, which means they can be divided into two equal parts that overlap perfectly when folded on the line of symmetry.  Lines of symmetry can be diagonal, horizontal, or vertical.

Here's a Study Jam to review line symmetry!

What forces cause erosion?

In Science, we've been learning about changes on Earth's crust.  Last week, we learned that water, wind, ice, plants, and temperature changes can weather rocks.

What happens to these pieces of weathered rock?

This week, we learned that water, wind, and ice (glaciers) can move weathered materials such as sand, soil, pebbles, rocks (even boulders!) during erosion.

Erosion in Action

When these forces can no longer move weathered materials, they are deposited, or dropped, in a new place.  This process is called deposition.

Erosion and deposition are big problems for some Floridians.  Check out this news clip to see Google Earth satellite images of beach erosion over the years in Ponte Vedra Beach, just south of us.

Here's a Study Jam on Weathering and Erosion.

So, fourth grade scientists, what is the difference between physical weathering and erosion?

Measuring Angles

Last week, we used a familiar tool to introduce benchmark angles.

Like benchmark numbers and benchmark fractions, benchmark angles are easy to visualize and useful in helping us figure out the measurements for other angles.

If we know that a right angle measures 90 degrees, then we can figure out measurements for all of these polygons' angles.

We found out that if we fill the space inside a right angle with the white rhombus' acute angle, it takes 3 to do so.  Since we know a right angle is 90 degrees, and all three parts are the same size, we can figure out the missing angles using addition:

90 degrees = _____ degrees + _____ degrees + _____ degrees

90 = 30 + 30 + 30

The white rhombus' acute angle is 30 degrees.

For each pattern block, we "solved mysteries", using what we knew and addition (sometimes subtraction) to figure out each angle's measurement.  We represented our solutions with equations.

Is it convenient to carry around pattern blocks whenever you need to measure an angle?  What if the angle you're trying to measure cannot be made by the sum of benchmark angles or the angles of pattern blocks?

You'll need a different tool:

A protractor is a tool used to measure angles.  Check out this Study Jam to review how to use one!  We'll be practicing measuring angles with protractors this week in class and next week for home learning.

Still unsure how to measure angles using a protractor?

 

A Sweet Lesson on Weathering

This week, we learned that weathering is the breaking down or wearing away of a rock.  We've read about how water, wind, ice, and plants can weather rocks.  Today we started testing how forces cause rocks to wear away with peppermints, sand, and jars.

 First each group gently shook their jar for 1 minute,

made observations,

 and recorded their observations with pictures or words.  We repeated this procedure 3 times, then did it again with another peppermint, but this time shook vigorously.

 From left to right: our control (a peppermint that wasn't shaken), a gently shaken peppermint (see the small chip at the top?), and a vigorously shaken peppermint (see how a bigger piece broke off at the top?).

 Most students also noticed a change in color as the stripes wore off.

Check out this crack after some vigorous shaking!

On Tuesday,  we'll debrief this activity to discuss the relationship between strength of forces and effect on rocks/Earth's crust.

Types of Lines

We're continuing to observe properties (attributes) of geometric figures, and this week, we're on the lookout for parallel, intersecting, and perpendicular lines.  Not sure what to look for?  Check out this Study Jam on Types of Lines.

 

Celebrating Black History Month

*Sometimes* I miss teaching Social Studies.  I love a good story, so I enjoy learning about peoples' lives.

Benjamin Banneker was born on November 9, 1731 in Ellicott City, Maryland.  Benjamin's parents were former slaves, but he was born free and raised on a tobacco farm where he attended school.  However, Benjamin learned science mostly through teaching himself.  He worked most of his life as a farmer, but he was also a successful problem-solver.  When Banneker was 24, he studied how clocks work by taking apart a watch, reassembling it, and making his own clock from wood.  He taught himself astronomy (the study of the moon and stars), and published a popular almanac (a book published every year that contains facts about the movements of the sun and moon, changes in the ocean's tides), Benjamin Banneker's Almanac, from 1792 to 1797.

Also a mathematician, Benjamin surveyed (made maps) of the land that was to become Washington, D.C.  Benjamin worked on calculating the precise measurement of meters.

Benjamin exchanged letters with Thomas Jefferson about slavery and how blacks were just as intelligent as whites. 

Benjamin never married; much of his personal life is now a mystery, as his papers and belongings were destroyed in a fire that occurred on the day of his funeral.

 I am looking forward to reading this book!

Classifying Quadrilaterals

This week, we started our geometry unit.  We've been learning attributes/properties of polygons to help us describe and identify these shapes.  We've looked at side length (line segments) and angles (right, acute, obtuse), and today we reviewed parallel and intersecting to help us describe lines and line segments.  Students were also introduced to perpendicular lines and line segments, or lines that intersect, forming right angles.  These new attributes/properties are extremely useful in describing and identifying the big family of quadrilaterals.

Here's a Study Jam to review what we learned today.