Learning with Catapults

Catapults from kitsMy boys love catapults.  Whether we are learning about early methods of warfare, watching Pumpkin Chunking’, or flinging marshmallows at each other – catapults are a constant source of engineering wonder.  Over the years the boys have built multiple catapults from kits as well as from scratch.

This year they were able to compete together in a Science Olympiad event called Ready, Aim, Fire!

IMG_0069The competition requires building a catapult of dimensions less than 65 cm x 65 cm x 65 cm powered only by a falling counterweight.  At the competition teams are given counterweights of 1 kg and 2 kg that are used to launch projectiles of 20-40g and 40-60g respectively.  Before the competition teams are expected to launch projectiles of various masses and record data.  The team prepares plots that are used to show where various projectile masses are expected to land.  On the day of competition the catapults are impounded.  After all devices are impounded, the judges announce the masses of the two projectiles that will be used that day.  Teams use their prepared graphs to determine how far they think their catapult will throw the projectiles and then tell the judges where they would like their target set in 0.5 m increments.

Launch scores (LS) are determined using the formula:

LS = TD – 3A +B

where TD is the target distance requested by the kids, A is the distance from where the projectile makes first impact to the center of the target and B is a bonus for hitting the target.  B = 0.15 x TD if the projectile hits the target and 0.30 x TD if the projectile stays in the target.   All distances are in meters.

Points are also awarded for graphing. (Up to 12 points).

This was a great project for the boys.  They handled much of the build themselves.  I helped out with a few of the cuts and my husband taught the boys to use the drill press.  My husband handled the original “basket” build with the boys making modifications later.

E recently had lessons in geometry and basic trigonometry, so he was able to use his knowledge of sin and cos to make the throw arm its maximum length while maintaining the optimum ratio of counterweight arm length to projectile arm length.   We also taught C the methods he was using.  It was a rather complex calculation so we set up a spreadsheet to do some iterations (side lesson on radians vs. angles was necessary).

The boys previous build experience came in very handy.  From the beginning they understood a trebuchet design would be best design for distance.  They also understood the importance of release angles and were quite keen at recognizing when the release angle was off and doing things to improve it.

Testing the trebuchet took quite a bit of time as they chose to make improvements to the basket and sling which required re-collecting all the data points they already had.  They used a spreadsheet to organize their data and select the trend line.

All their hard work paid off when they were able to make accurate predictions the day of the competition.  They were able to hit the target on the 1 kg launch and come very close on their 2 kg launch (the ball landed just a bit to the right).

Boys with TrebuchetIt was a very exciting day for them.  They were thrilled to take home first place medals and they are already looking forward to competing in the middle school division next year.

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Weekly Wrap-up – FABulous field trips and other creative pursuits

FIELD TRIP!!  Field trips are one of my absolute favorite things about homeschooling.  Field trips, individualized learning, treating kids with respect, building projects, time in nature – they are all my favorite things.

Last Friday we went to University of Pittsburgh to check out their Human Engineering Research Laboratories.  They work with the Veterans’ Administration to develop better assistive devises like wheelchairs, prosthetics, and orthotics.   It was great career exposure for the kids.  The combination of engineering with making a real difference in other people’s lives is a very appealing concept.

It just so happened there was also a place across the street called TechShop.  They were offering tours so we stopped in along with some friends who were also on the aforementioned HERL tour.  What a cool place!  It’s a FAB Lab on steroids.  They have the typical laser cutter/engravers, 3D printers, vinyl cutters and wood shop, but they also have a water jet cutter, a powder coat paint booth, welding, and CNC machines.  They also have a great textile station with embroidery and screen printing and a computer workshop area.   Check out the website and take a tour if you happen to live near one.

IMG_1835After lunch we headed over to the Carnegie Science Center.  It was such a short visit we only had time for the sports area, the traveling H2O exhibit and the shuttle lift.

IMG_1847This week we had the opportunity to attend a Cleveland Orchestra Education Concert.  The orchestra does a great job selecting the music for these concerts.  This one started with the Imperial March from Star Wars then moved on to classical composers like Vivaldi and Bach.  They also did a couple of American Jazz pieces before concluding with a part of the E.T. score.  The boys are really so so about going to the orchestra, but I just adore the chance to hear the orchestra perform.  I also love the architecture of Severance Hall.

After the performance we had lunch with friends and went through the “swords and knights” exhibit at the art museum.  We also went through the modern art section which is always fun.  The art museum is free which makes it easy to just pop in for a few minutes.  After the art museum we headed over to the Natural History Museum for about an hour before heading home so we could get ready for swim lessons.

Going on field trips means lots of time in the car so we listened to the first book of the Redwall series by Brian Jacques.  The story was very action packed and exciting.  If it had been a print edition, I would say it was a real page turner.  We listened to several hours of the story on Saturday and Sunday as well.  We will certainly be listening to more of the Redwall series during car trips this summer.

IMG_1857We had some good weather this week, which allowed us to work on our catapults.  They are almost complete, but on hold again while E is away on a camping trip this weekend.

Having the chance to visit so many creative spaces this week has been really invigorating.  I’m really looking forward to working on some creative projects this summer.

What fun projects are you planning for summer?

Weekly Wrap-Up WUH

Weekly Wrap-up – Lots of Science

This week we concentrated on science and easing back into math.

Botanical Garden Butterflies

We took a field trip to the Cleveland Botanical Gardens to visit the Nature Connects Exhibit before it closed.  I sometimes forget how much I enjoy going to gardens and arboretums.


We continued our unit study of atmospheric science.  This week we drew representations of the layers of the atmosphere and learned more about the phases of water and hydrogen bonding.

Solar Bag in Flight

It has become a yearly tradition to do a solar bag experiment at the local park.  This year it tied in really well with our science unit.

We’ve added back in math.  One day C practiced his math facts by putting post it notes around the trampoline and running to the correct answer.  It was fun and active, but still a great review.

The FIRST LEGO League challenge was released this week.  This year the challenge is “World Class Learning Unleashed” and the teams will be figuring out an innovative way for people to learn about a topic of their own choosing.  Both boys met with their FLL teams and I’m confident we will be off to a good start.  We don’t have our table built yet, but the boys laid out the robot game configuration anyway.

Hope your year is off to a great start!

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Weekly Wrap-Up WUH      Mary_CollageFriday

Atmospheric Science – Part 3 – Solar Science

It has become a bit of a tradition for us to open the school year with a solar bag experiment.

Unfurling the Solar Bag


The solar bag is rather like a very thin black garbage bag only much much longer.

Solar Bag Filled


Once the bag is filled we tie it off and add a string.



Then we wait a few minutes for the air in the bag to heat up.  This year we had a nice conversation about radiant energy and convection while we waited.  We were also careful to observe that we could visibly see the bag had expanded.

Solar Bag in Flight

Eventually the bag was floating high in the sky.

You might notice a lot of clouds in the pictures.  The clouds caused a lot of rise and fall of the solar bag.  In past years, we have done the experiment on clear sunny mornings.  Clear sunny days are certainly best for having the bag flying for a long time, but the cloudy day really illustrated the importance of radiant energy from the sun.

We sourced our bag from Steve Spangler Science. (not an affiliate link)  If you choose to do this experiment make sure to choose a large grassy field and bring along transparent tape and scissors.

Hope you are having a great school year!

Atmospheric Science – Part 2

We are continuing our study of atmospheric science using lesson plans from UCAR with our own twist.  The activity today closely followed Introduction to the Atmosphere – Activity 3.  

Today’s activity was short, but packed with important concepts.

First we watched the following short videos from the Canadian Museum of Nature:

Part 1

Part 2

I emphasized to the boys that not all molecules are polar.  The polarity of water gives it properties that are important.  The polarity is introduced due to an uneven sharing of the electrons that create the bond between hydrogen and oxygen.

After viewing the videos,  we used paper plates and M&Ms to make models of water in it’s solid, liquid and gas states.


C chose to use single M&Ms to represent each water molecule.  This representation allowed us to shake the plate rapidly to represent gas molecules and more slowly when representing molecules in the liquid state.  He glued the molecules to the plate when representing ice and drew in the hydrogen bonds.

We briefly discussed that it is a combination of pressure AND temperature that effect the state of matter, but for our purposes we would be discussing water at a constant atmospheric pressure.  We also reviewed the temperatures at which state changes begin to occur in both Celsius and Fahrenheit at atmospheric pressure.



E chose to emphasize the  H2O structure of water.  The disadvantage was we couldn’t shake the gas and liquid plates, but we were more clearly able to see the need to line up the hydrogens facing the oxygen in the solid state.

Both boys used a roughly equivalent number of molecules in their solid and liquid representations.  We ended up moving a couple of molecules from solid over to liquid to emphasize that ice is less dense than water, which they knew but just didn’t think to count the number of molecules in each plate.

The shape of the arrangement and hydrogen bonds didn’t turn out exactly right in the models, but they did understand the concept of attraction between slight positive and negative charges that are easily overcome at higher temperatures (faster vibration).

Between the videos and the models the boys were able to clearly understand why ice is less dense than water and why that is a “special” case.  They were also able to grasp that hydrogen bonding between molecules is a much weaker force than the sharing of electrons between atoms, yet the hydrogen bonds are important in creating the structure of ice and causing it to float.

In addition to the lesson plan I think it is worth pondering some of the ways our world would be completely different if ice weren’t slightly less dense than water.  How would that impact life in ponds?  What about polar bears?  What about the planet as a whole?

Periodic Videos offers some thoughts on the importance of the density of ice:

Hope you are having a great day exploring the world around you!



Atmospheric Science – Part 1

This summer as I was trying to find a good answer to a particular science question,  I found a lesson plan that really did a great job answering the given question and giving a hands on activity that illustrated the concept well.  Then I realized the lesson plan was part of an entire set of Atmospheric Science lesson plans from the University Corporation for Atmospheric Research designed for middle school teachers.  The more of the plans and activities I read through the more I thought –  “These will be great to use with the boys! ”  There are lots of suggestions for hands on activities that will appeal to a variety of learning styles.

Today we started out with the boys telling me what they already knew about the atmosphere.  Then we read through about the first half of the Intro to the Atmosphere lesson.  After that we were ready to start with one of the suggested hands on activities.

Atmospheric Science - Sorting the M&Ms

What could be better for the first day of school than counting M&Ms?

Atmospheric Science - Representation of Earth's Atmosphere

First we counted out 78 Blue M&Ms to represent the amount of nitrogen in Earth’s atmosphere. Then 21 green M&Ms to represent oxygen and 1 brown piece to represent Argon.  There is a fleck of red in there somewhere to represent the 0.03% carbon dioxide.

Atmospheric Science - Earth, Venus, and Mars

Next we used the same color system to represent the make up of the atmospheres of Venus and Mars.

In addition to the planned topics, we had some great discussions about the contribution of plants to our environment, the water cycle, and ozone.  Then it was time for the best part:

Atmospheric Science - Eating the M&Ms

Eating some of the M&Ms!

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        Hip Homeschool Moms




With Easter coming up it’s a great time to do some egg-perimenting.


Egg in a Bottle – I’d been wanting to do this experiment forever, but hadn’t been able to find a jar with a neck the correct size.  I finally discovered that Starbucks Fraps come with the perfect egg-sized neck.   We used a candle held upright in a pinch of play dough as the combustion source in the bottle.  Light the candle and top the bottle with a PEELED boiled egg.  As the air inside the bottle heats and the pressure increases the egg will dance around releasing air from the bottle.  Once the flame goes out and the air cools the egg should be sucked down into the bottle.

Egg Spin

Spinning Eggs – This one is so wonderfully simple!  Spin a hard boiled egg and an uncooked egg and observe the difference.

Egg Toss

Egg Drop –  Use plastic grocery bags, sponges, strings, balloons, tape and/or pipe cleaners to make parachutes for eggs and then toss them off the play set.

Illuminated Naked EggNaked Egg – Soak a few uncooked eggs in vinegar for a couple of days.  The vinegar will eat away the shell but leave the membrane.  The vinegar also permeates the membrane and swells the egg.  As a follow up try soaking the egg(s) in corn syrup.

Natural Egg Dyes – You can find a list of natural dyes to try at Better Homes and Gardens.    Red cabbage is supposed to produce a nice blue color on the eggs.

Color MixingUse regular egg / food coloring to do color mixing experiments.

Use Egg Shells as containers for Seedlings 

Egg Walk



Walk on Eggs – We saw this one posted somewhere and I thought why not give it a try.  The key is to go quickly and stay well balanced.  One of the boys did it effortlessly without any broken eggs.  The other…..well let’s say we all had a terrific laugh and the kitchen floor got mopped.








That’s the end of our list for now.  So break out the eggs and have some fun!



Engineers’ Week Past

Back when I was in Engineering School, we always celebrated Engineers’ Week right around St. Patricks Day, because St. Pat was an engineer.  You didn’t know that?  It’s true – he created the first  “worm drive”.  (Ba-dum-dum)  Okay, so the joke hasn’t gotten any better, but it is really fun to have an Engineers’ Week.

Last year our celebration was pretty spontaneous.  We purchased marshmallows, toothpicks, straws, and cups for building.

Engineer's Week - Green Boat Engineers Week - Boat

The boys found some left over foam supplies and built boats.  Since it was cold outside the stairs became the test ground for the boats.  The objective was to safely get your LEGO mini-figs down the stairs in your boat.

Toothpick Ferris Wheel

They had a great time making marshmallow and toothpick towers.  E even made a ferris wheel.

The Great Wall of China

We also happened to be studying ancient China, so after making several marshmallow creations and cup towers the boys built their own version of the Great Wall and attacked it with LEGO mini-figs and catapults.


On Chemical Engineering Day, we explored non-Newtonian fluids by mixing up a batch of oobleck.  Start with equal parts water and cornstarch then make additions until you have a liquid when the mixture is uncompressed and a solid when under pressure.

Red Cabbage Indicator



We also tested the pH of a variety of substances using red cabbage as the indicator.  You can make a pH paper from the cabbage juice, but we preferred using the cabbage right out of the food processor.

Chocolate Pi








On 3/14 we celebrated Pi day by making and eating Chocolate Pie.

Swiffer Bot








On computer science day we messed around a little on Scratch and E built a “Swiffer Bot” for me using his NXT.









We finished up the week by taking a field trip to the science center.






We had a ton of fun with lots of hands on learning!  The boys really got into it and they are looking forward to having another Engineers’ Week this year.

This year we are planning to celebrate Engineers’ Week March 10 – 16.   I’m working on a list of ideas to share with you all soon!

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4 Reasons Kids Really Like FIRST LEGO League


First let me say congratulations to the RoboTigers!  They had a great showing at their regional tournament and they are moving on to districts!  They won awards for Robot Design and the Regional Ambassodor Award for their work telling other kids about FLL.

FIRST LEGO League (FLL) is a great program designed to get kids interested in STEM activities and careers.  The entire FIRST program spans kindergarten through 12th grade with the FLL portion geared toward kids 9-14.

Each year the competition centers around a new theme.  This year the theme is Nature’s Fury – Prepare. Stay Safe. Rebuild.  Teams chose a community and a specific natural disaster the community faces.  The teams researched the problems people in the community face and came up with an innovative solution to help the community prepare, stay safe, or rebuild after natural disasters.  The teams are also expected to share their ideas with the people they want to help.

This summer some members of the RoboTigers were caught outside during a tornado warning with only a pavilion for shelter, so they decided to help their community better prepare for tornadoes.  The team researched tornadoes by skyping with a meteorology grad student, emailing a professor studying tornado safety, and reading about research regarding helmet use in tornadoes.  They also surveyed kids in their community and kids from Oklahoma to find out what they knew about tornadoes and tornado safety.  From their research they learned that most injuries in tornadoes are caused by debris.  They decided to create a portable Debris Protection System.


They designed an experiment to test the suitability of different materials.  Then they designed a few Debris Protection Systems using bike helmets, safety glasses, gloves, and “leather” capes.


They presented the Debris Protection System at a city council meeting and at a Cub Scout  Meeting.

The other portion of the FLL competition is the Robot Game.  I’m sharing a short 2:30 video of the RoboTigers at competition.  Not everything went correctly that day.  Sometimes that is just the way things work, slight variations in the table or mat between home and competition can make a difference.   For a complete overview of missions in this years robot game you can check out the official 28 minute video.

So what do the KIDS really like about FLL?  I asked the RoboTigers to tell me their favorite thing(s) about FLL.

1. It’s FUN.  They have a great time together as a team.  When they are really putting in the final push to get ready for a tournament they frequently eat meals together and have plenty of time to goof around.  Another nice aspect is the team stays together year after year.

2. Programming.  The RoboTiger team makes sure all the kids participate in programming the robot.  They really enjoy the sense of accomplishment when their mission works.  There is something really satisfying about making a robot do what you want it to do.

3. The Robot Game – The tournament atmosphere is really fun and high energy.  The kids have fun building the props for the missions and nicknaming the characters.  They enjoy planning the missions, running the programs and designing the attachments.

4. Designing an Actual Prototype – They enjoy the chance to come up with real world solutions.  This year they were able to develop a complete Debris Protection System and spread awareness that wearing a helmet during a tornado can save your life.  FIRST provides a great opportunity for kids to have their ideas heard and respected.

If you have a son or daughter you think might be interested in FLL stay tuned.  I’m working on more posts – including how to start a team and the aspects of FLL parents and coaches really appreciate.

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List_it_Tuesday      Highhill Homeschool

Candy Making: Snow and Cold Weather Science Part 3

Want a science activity your kids will love?  Try making candy!  It’s more of an observation experiment as the hot sticky syrup requires adult handling, but it’s fun and tasty.


The first time we did this activity the kids were amazed that pure sugar candy was really just sugar with a tiny bit of flavoring.   We’ve used just sugar and we’ve  used the kit from Hobby Lobby that comes with some powdered corn syrup.  I thought it went faster when we used the kit but I didn’t time it.


The nice part about the kit is that it comes with a couple of reusable molds.



I added blue food coloring and raspberry flavoring.  Somehow before the process was done the blue reacted with the flavoring and turned green.



The trays that come with the kit are really handy.  Once we tried making candy without using the molds and we ended up with lots of sharp edges.

If you are using the kit there is more mixture than what fits in the molds so have some aluminum foil or wax paper handy to make extra shapes.

This activity ties in well if you are studying crystals, saturation, or phase changes.  It is also a good time to review melting and boiling points in F and C and emphasize that 0 and 100 C are the melting and boiling points for water at 1 atm pressure.  Other substances have different melting and boiling points.

Wishing you many happy science experiments!