Secular Science Resources for Homeschoolers



High School Biology 08 – Cytosis: A Cell Biology Board Game

We spent the whole class playing a game today.  I got Cytosis: A Cell Biology Board Game, the Collector’s Edition, last year from Kickstarter.  I’m not sure if you can still buy the collector’s edition, but the regular version is available on Amazon.  I believe the only difference is that the macromolecule pieces in the collector’s edition are different shapes while in the regular version they are all cubes. In the photo below you can see the flasks which players place around the board to gather resources (lipids, ATP, or mRNA), or to build macromolecules like carbohydrates (green pieces) and proteins (red pieces).


Players collect resources and build macromolecules, gaining health points for each completed molecule.  There are lots of different ways to get bonus points using goal cards, hormone recepter cards or making sets of enzymes.  It comes with a virus expansion pack but its complicated enough without adding viruses.  There are 8 kids in my class so we had 4 play while the other 4 watched and helped and then switched half way through class.  The game can be played by 2 – 5 players.  My son and I played the 2


player version a few times before class so we’d know how to play and could help the other players.  It was pretty fun with both 2 and 4 players and I think it does help get across some points, like ATP is the currrency of the cell, since you need to ‘pay’ ATP to get your molecules out of the cell, or to make an enzyme, etc.  You also have to move your transport vessicle from the endoplasmic reticulum to the golgi appartus to finish buiding your molecule before taking it to the cell membrane to exit by exocytosis.

We did discover one problem, if you have a color blind player you might want to go through the cell component cards and label the red or green cubes with a P for protein (red) or C for carbohydrate (green) since they look the same for people who are red-green colorblind.  Its too bad they didn’t use the shapes on the card because that would have eliminated that problem.

They have a video on youtube explaining how to play and I recommend starting there

and then reading the instructions.  It looks pretty complicated but once you go through a round or two everyone seems to catch on.   It takes a bit over an hour to complete a game and its hard to tell who’s winning since there are a lot of bonus points at the end of the game to score.  One player got over 20 extra points at the end because she had 2 sets of enzymes which are worth a lot and she had put a goal marker on the enzyme goal which gave her even more bonus points for each enzyme – she won!

IMG_8976If you have students who like to learn via game play then Cytosis is probably a good buy. There is separate booklet in the game explaining the biology behind all the game components.



Middle School Biology 06 – Stomata

I asked students to bring leaves to class today and they took small pieces of them and looked at them in the microscope.  Since most leaves are too thick (many layers of cells) to see much with the light coming through the leaf, I had students turn off the microscope light and shine a flashlight on top of their leaf sample.  The goal was to find stomata – the small holes on the bottom side of leaves that allow the plant to exchange gases with the outside world, so students focused on the underside of leaves.

They also tried making thin slices of leaves and making a wet mount slide.  Here are some of the photos from our observations.

stomata, stoma on donkeytail leaf
Here’s the best photo I got of a stoma, I believe this was at 400x and was a very thin slice off a donkeytail succulent.  The ‘mouth’ like structure in the middle of the photo is a stoma.  Now you know what you’re looking for in the other photos.


Most leaves will give you something like this at first glance, with light coming from below the slide.  You can actually see a few stomata on this one if you zoom in but I’m not sure its going to be high enough resolution on this website.
Stomata were easy to spot on this yellow leaf.
Same photo just zoomed in and cropped.  

The photo below is the surface of a fuzzy leaf (tree mallow).  I was amazed when I first looked it under the microscope. All the little pointy structures  are what give the leaf its fuzzy texture.  Not much hope of seeing stomata on this complex surface.  The photo below was lit from above with a flashlight.IMG_8847

When the students were tired of looking through the microscopes I walked them through the Energy In, Energy Out activity from Chapter 6 in RSO Biology Level 2, from Pandia Press.  Students had a drawing of a leaf with stomata (look like 2 cheese puffs side by side) and ovals already drawn on it.  I had them make green dots representing the chloraplasts in the ovals.  They also drew some carbon dioxide, oxygen, glucose and water molecules and arrows showing where they are made, or enter/exit the leaf.  There was a second worksheet that showed trees and students drew themselves into the landscape, along with some bugs, dogs, cats and a unicorn or two and again drew oxygen, carbon dioxide and water  with arrows showing how they cycle through animals and plants.IMG_8959.jpeg

Microscope photos were taken with my iPhone and the Celestron NeXYZ smart phone adapter.

High School Biology 07 – Osmosis continued & Energy

Students were asked to watch the following videos before class:

and if they wanted more they could watch Crash Course and Bozeman Science:

Last week we soaked eggs in karo syrup and water and measured their change in mass due to osmosis after two hours.  We put the eggs back in the solutions at the end of class and I had some students measure them one more time a few DAYS later and the mass change of the egg sitting in Karo syrup was dramatic.  As you can see in the photo below, the egg in the lower left part of the photo has been reduced to basically just the yolk in an empty membrane, while the egg in the lower right of the photo looks and feels very full.  The egg on the left had been soaking in karo syrup for over 2 days and the egg had lost half its mass as the water inside the egg diffused out into the karo syrup.  The egg on the right was submerged in regular water and actually gained 7g in mass because water diffused into the egg, since it had a higher concentration of solutes than the plain water outside the egg.  IMG_8703

I gave the students in this class the final set of masses and a copy of the above photo to put in their lab books.

After a presentation on energy and exergonic (releases energy) and endergonic (absorbs energy) reactions, we did a lab (6.2 Endergonic and Exergonic Reactions in Holt Biology Instructors Guide) demonstrating both types of reactions.   Students put 75 ml of room temperature water in a beaker, measured its initial temperature and then added 15 g of calcium chloride (or 15 g of ammonium nitrate) to the water and observed the temperature change of the water.   Calcium chloride can be bought at a hardware store as DampRid (among other names).

I have a Vernier Go Direct temperature sensor which can be used with an iPad to record the temperature throughout the reaction which we used for both reactions. The graph below shows the data for ammonium nitrate.  The water was initially 24 C and dropped to 20.5 C.  For this particular data set, only 9 g of ammonium nitrate was used because we didn’t have enough for both groups to use 15 g.  The other group used 13 g and their temperature dropped to 14 C, which was a pretty dramatic difference to the touch (on the outside of the beaker).  The graph below is not smooth because we would swirl or stir the solution once in a while to increase the reaction and then the temperature would drop again, like you see at 80 s.ammonium nitrate

The graph below shows the same experiment with calcium chloride. This graph ends a little early but students continued to observe the temperature and it went up to 40 C before plateauing.

calcium chloride

Calcium chloride added to water is an exergonic reaction – it releases energy which heats up the water, while ammonium nitrate added to water is an endergonic reaction – it absorbs heat from the water, decreasing the temperature of the water.

I had hoped to play Cytosis, a cell biology game I got off kickstarter last year but we ran out of time, so we’l try that next week.  In the time remaining I had the students do the same interactive notebook activity on cellular respiration and photosynthesis that the middle school kids did.


Middle School Biology 05 – Photosynthesis

I gave a short presentation on photosynthesis at the beginning of class and we watched the following Ted talk:

If you have the Horrible Science books, Vicious Veg is a good book to read on this subject.  For the activity the students played the photosynthesis formula game I found on Ellen J McHenry’s website. They used pony beads to represent atoms and they had to IMG_8757spin to gather resources (water, carbon dioxide and sunlight) until they had enough of everything to undergo photosynthesis (everything on the top part of the sheet), at which point they took apart the molecules and built a glucose molecule and used the remaining atoms to make water and oxygen molecules – the products of photosynthesis on the bottom of the sheet.


The first students to build the glucose properly got to eat some gummy bears (they were originally going to be used for osmosis experiments but the egg experiment is more dramatic).   You can see in the photo we used  pipe cleaners to make small molecules with the beads and one big pipe cleaner to be the ring in the glucose, with smaller pipe cleaners going through the carbons to attach the extra H and OH.   If students had extra pony beads left over, that was a clue that their glucose was incomplete.  This helps get across why you need 12 water molecules and 6 carbon dioxide molecules to get just one glucose.

IMG_8777Students also did an interactive notebook activity on photosynthesis and cellular respiration, which is pretty much the opposite of photosynthesis.  Plant cells do photosynthesis to create glucose  and oxygen, which animal cells use cellular respiration to break down glucose and oxygen to get energy (ATP) and carbon dioxide. Students had to cut out squares with the names of the different molecules and descriptions of the process and put them in the right place.  I got this activity from the Cells Interactive Notebook by Getting Nerdy with Mel and Gerdy that I bought on

High School Biology 06 – Osmosis

Students were asked to watch the following videos before class:

We did two different labs today, osmosis with a chicken egg and osmosis with red onion cells.  The first lab is from the Biology: Life on Earth online resources and can be found in the instructor guide for Chapter 5, Lecture Activity 5.6: Demonstration of Osmosis.

Eggs, soaked in vinegar for 48 hours, rinsed and sitting in water.

This lab requires that you soak a few eggs in vinegar for 24-48 hours to remove the calcium shell, before doing the lab.  Students blotted the eggs with paper towels and found their mass using a digital scale.  IMG_8667We then put 2 of the eggs in plastic cups full of water, 1 in a cup of Karo syrup (light corn syrup) and 1 in a cup of 20% salt water.  Every 30 minutes we took the eggs out, blotted them dry and measured their mass.  As predicted, the eggs in the hypertonic soluntions (corn syrup and salt water) lost mass as the water inside the eggs diffused out into the solution in an effort to dilute it.  The eggs in water gained a small amount of mass as the water entered the egg, since it has the higher concentration of dissolved materials than outside the egg.  I’m going to keep these eggs submerged in their different solutions for a few days so we can get one more data point. (Click here to see more on this experiment)

While we were between measurements on the egg experiment, students made microscope slides with thin slices of red onion skin.  This is an AP Biology lab, Osmosis in a Plant Cell and can be found online at  Once they had a nice view of the red onion cells through the microscope, they sketched a cell or two or took photos.  Then they put a few drops of 15% salt water on one edge of the slide and held a paper towel to the other side to draw the salt water across the red onion sample – this was done with the slide on the microscope so we could observe the reaction of the cells.  The photo on the left below is red onion cells in water and the photo on the right shows the affect of salt water on the cells.


I bought a new smartphone adapter to use with the microscope, the Celestron NexYZ, and was able to take some nice time lapse photos of the red onion cells membrane shrinking as the water leaves the cells and enters the salt solution surrounding it. The Celestron adapter is a big improvement over the Carson one I had before. It has 3 knobs to move the phone in X, Y and Z direction just like the translation stage on a microscope, which makes it easy to line up the phone’s camera.  It also has a lock to make it more secure on the microscope but I still found I had to hold it up the far end of the phone just a bit.


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