Lesson	Plan	

Author:	 Molly	Albecker

Author	Affiliation and	

Location:

East	Carolina	University,	Greenville,	NC

Optional	Author	Website http://albeckerm09.wix.com/mollyalbecker

All	resources,	worksheets,	PowerPoints,	and	videos	can	be	accessed	from	my	website.

Author	Contact	

Information	

albeckerm09@students.ecu.edu

Introduction/Abstract	to	

Lesson	Plan	

This	lesson	plan	uses	real-world	ecological	dynamics	to	introduce	students	to	the	

scientific	method.	The	students	will	learn	the	process	of	observation,	hypothesis,	

experimental	design,	data	collection,	and	drawing	conclusions	that	support	or	do	not	

support	their	hypotheses	via	a	simple,	classroom	experiment.	

Learning	Objectives	 At	the	completion	of	this	lesson,	students	will	be	able	to	describe	the	scientific	

method,	formulate	hypotheses,	setup	an	experiment,	collect	data	and	plot	on	a	graph,	

evaluate	and	interpret	results,	and	make	conclusions	about	the	ecological	dynamics	

that	amphibians	experience	in	their	wetland	habitats.	

Appropriate	Grade	Levels 9-12	

Group	Size/#	of	students	

activities	are	designed	for

<30

Setting	(e.g.	indoors,	

outdoors,	lab,	etc.)

Indoor	classroom.	Egg	masses	will be	collected	by	the	teacher	outdoors.

Approximate	Time	of	

Lesson

~45	minutes	for	the	initial lesson.	It	will	take	approximately	1.5	-3	months	for	tadpoles	

to	metamorphose	with	periodic	20-30	minute	teaching	points.	

Resources	Needed	for	

Students

Internet	access,	computer/notebook	for	taking	notes

Resources	Needed	for	

Educators

4	Clear	Tupperware	containers	or	4	small	aquariums,	Frozen	spinach (or	fish	flakes),	

Dechlorinated	tap	water	or	pond	water,	small	aquarium	net.	Salt,	teaspoon,	Supplied	

datasheets for	data	recording (Found	on	website).	(Optional:	scale	for	weight	

measurements,	water	dechlorinator).

Apps/Websites	Needed

Lesson	Activity	 1. Introduce	students	to	the	project using	powerpoint (on	website). Information	

on	habitat,	characteristics,	requirements,	and	life	cycle	will	be	introduced.

Additionally,	the	scientific	method	will	be	outlined	and	the	experiment’s	

protocols	will	be	introduced and	discussed.

2. Have	students	gather	around	the egg	mass	that	you	collected	and	engage	the	

class	in	a	discussion	based	on	what	they	just	learned.

3. Set	up	the	experiment	with	student	observation	(Protocols	in	powerpoint).	

4. Students	should	write	hypotheses	and	justify	them.	

5. Over	the	next	few	weeks,	students	observe	the developments	and	record	their	

observations.	

6. Students	wait	for	metamorphosis	and	date	and	number	that	emerge	each	day	

(generally,	tadpoles	metamorph	around	the	same	time,	within	a	week	of	the	

first).	The	response	variable	that	we	are	interested	in	is	the	amount	of	time	to	

metamorphosis.

7. Optional:	Have	one	or	two	students	weigh	the	metamorphs	as	they	emerge	

and	record	the	weight	of	each.	This	will	yield	an	additional	response	variable	of	

“weight	at	metamorphosis”.	This	can	be	tricky	though,	as	the	froglets	are	very	

small,	difficult	to	handle,	and	can	be	surprisingly	jumpy.
8. Place	the	metamorphs	in	a	separate,	container	to	be	released	to	a	wetland	

(husbandry	techniques	outlined	below).

9. Enter	data	into	Excel	and	create	a	graph	using	the	time	to	metamorphosis	

and/or	weight at	metamorphosis	according	to	treatment.

10. Questions	for	students:	Is	there	a	pattern	in	the	data?	What	is	the	pattern?	

11. Have	students	write	lab	report	on	the	activity.	A	lab	report	format	sheet	and	

suggested	rubric	are	available	on	the	website.

Final	Product	 A	lab	report on	the	experiment	including	an	introduction	(including	independent

research	accomplished	by	the	student),	hypotheses,	a	description	of	the	experimental	

design,	a	graph depicting the	results	(can	be	excel	or	hand	drawn),	and	the	conclusions	

with	clear	assessment	of	whether	or	not	their	original	hypothesis	was	supported.	

Assessment/Evaluation Lab	reports	can	be	graded.	A	suggested	rubric	for	grading	is	provided	in	the	

supplementary	materials.

NC	Essential	Standards Bio.1.2.1:	Explain	how	homeostasis	is	maintained	in	the	cell	and	within	an	organism	

in	various	environments	(including	temperature	and	pH).	

• To	maintain	homeostasis,	tadpoles	must	maintain	a	water	balance.	If	tadpoles	

are	placed	in	a	habitat	with	high	solute	(hyperosmotic)	concentrations,	they	

will	need	to	use	energy	to	actively	pump	out	excess	solutes	to	stay	alive.	This	

means	that	energy	that	would	otherwise	be	used	for	growth	is	used	for	the	

homeostatic	demands.	

• How	will	that	affect	their	weight at	metamorphosis	and	how	long	that	it	takes	

to	metamorph?	

Bio.2.1.4:	Explain	why	ecosystems	can	be	relatively	stable	over	hundreds	or	

thousands	of	years,	even	though	populations	may	fluctuate	(emphasizing	availability	

of	food,	availability	of	shelter,	number	of	predators	and	disease).

• Animals	face	environmental	stressors	ranging	from	disease,	predators,	

competition,	and	food	shortages.	In	each	case,	animals	will	adapt	or	the	

strongest	survive.	If	only	the	strongest	survive,	they	will	be	better	able	to	

capitalize	on	the	opportunities	by	better	avoiding	predation,	exploiting	food	

sources,	outcompeting	others	for	resources,	and	avoiding	infection.	

• What	can	we	infer	about	a	tadpole’s	ability	to	endure	salt	stress?	Will	they	be	

better	or	worse	off	after	enduring	the	osmotic	stress?	(Answer:	depends	–

they	will	probably	be	smaller	which	may	mean	fewer	breeding	opportunities.	

They	may	be	better	able	to	survive	salty	conditions	as	adults	however.	

Emphasize	trade-off.)

Bio.2.2.1:	Infer	how	human	activities	(including	population	growth,	pollution,	global	

warming,	burning	of	fossil	fuels,	habitat	destruction	and	introduction	of	nonnative	

species)	may	impact	the	environment.

• We	are	learning	how	a	“natural”	component	of	ecosystems	can	affect	tadpoles	

but	many	ecosystems	are	laced	with	various	pollutants	and	chemicals.

• Discuss:	What	about	human	caused	pollutants- How	might	the	principles	we	

learned	in	this	lesson	help	us	understand	how	tadpoles	are	affected	by	

pollutants	and	other	introduced	chemicals?	

Bio.3.2.3:	Explain	how	the	environment	can	influence	the	expression	of	genetic	

traits.

• As	tadpoles	are	under	osmotic	stress,	they	will	up-regulate	the	transcription	

and	translation	of	genes	that	code	for	sodium-potassium	pumps.	Since	the	gills	

are	the	primary	sites	of	excess	solute	excretion,	they	can	increase	the	numbers	

of	sodium-potassium	pumps	in	the	cells	that	comprise	the	gill	tissues	to	help	

get	rid	of	excess	salts.

Bio.3.4.2+Bio.3.4.3: Explain	how	natural	selection	influences	the	changes	in	species	
over	time,	and	how	various	agents	can	influence	natural	selection.

• Questions	for	discussion:	How	might	salt	stress	influence	the	natural	selection	

of	the	tadpoles	in	that	salt-invaded	habitat?	

• Answer:	To	adapt	to	this	environment,	tadpoles	must	be	able	to	excrete	the	

excess	salt.	Some	individuals	may	have	an	adaptation	that	allows	them	to	

excrete	the	salts	with	very	little	energetic	cost.	Therefore	they	may	have	more	

energy	to	acquire	food,	grow,	escape	predators,	and	metamorphose.	

Therefore,	these	individuals	may	have higher	rates	of	reproduction	and	

therefore	pass	the	advantageous	adaptation	to	its	offspring	(assuming	it	is	a	

heritable	trait).	

Bio.4.1.2+Bio.4.2.2:	Summarize	the	relationship	among	DNA,	proteins	and	amino	

acids	in	carrying	out	the	work	of	cells	and	how this	is	similar	in	all	organisms,	Explain	

ways	that	organisms	use	released	energy	for	maintaining	homeostasis	(active	

transport).

• A	portion	of	the	DNA	code	is	translated	and	transcribed	into	the	amino	acids	

that	make	up	the	sodium-potassium	pumps	(proteins).	These	active	transport	

pumps	are	crucial	to	maintain	a	proper	osmotic	balance	in	all	living	organisms,	

including	humans. They	do	require	the	use	of	energy	that	is	released	from	ATP	

(Adenosine	TriPhosphate).	

Next	Generation	

Standards

HS-LS1-3:	Plan	and	conduct	an	investigation	to	provide	evidence	that feedback	

mechanisms maintain	homeostasis.

• Maintaining	osmotic	balance	is	a	fundamental	process	in	maintaining	homeostasis.	

This	experiment	highlights	osmotic	stress	and	the	costs	associated	with	actively	

maintaining	water	balance.	

HS-LS4-2:	Construct	an	explanation	based	on	evidence	that the	process	of	evolution primarily	

results	from four	factors:	(1)	the	potential	for	a	species	to	increase	in	number,	(2)	the	

heritable	genetic	variation	of	individuals	in	a	species	due	to	mutation	and	sexual	

reproduction,	(3)	competition	for	limited	resources,	and	(4)	the	proliferation	of	those	

organisms	that	are	better	able	to	survive	and	reproduce	in	the	environment.

• As	discussed	before,	this	experiment	may	demonstrate	that	some	individuals	are	

better	able	to	tolerate	the	osmotic	stress	of	a	salty	larval	environment.	If	these	

differences	are	genetic	and	heritable,	the	individuals	may	produce	the	next	generation	

of	tadpoles	that	can	handle	osmotic	stress	better	than	others	and	capitalize	on	

resources.	

• In	their	lab	reports,	students	should	indicate	a	basic	understanding	of	these	principals	

but	also	understand	that	natural	selection	involves	a	tradeoff	between	energetic	

demands	(osmotic	balance	vs.	growth).	The	particular	environment	will	dictate	which	

particular	strategy	is	more	adaptive	(salty	environments	will	likely	select	for	ability	to	

regulate	osmotic	balance	well,	while	other	environments	may	select	for	the	ability	to	

grow	fast	and	metamorphose	quickly	to	escape	predation	or	a	food-starved	larval	

habitat.)
Images:	

Egg	mass	pictures:	

Sample	aquaria:	

Notes:	

Egg	mass	collection: Around	the	end	of	February,	frogs	will emerge	from	hibernation	and	begin	to	breed.	The	easiest	

method	to	find	a	wetland	first	involves	finding	a	productive	wetland.	To	find	one,	drive	around and	listen	for	frogs	on	a	

warm,	rainy	night	(no	need	to	get	wet,	just	listen	from	the	car!). Frogs	are	eager	to	breed	and	will	lay	eggs	in	water-filled	

roadside	ditches,	tire	ruts,	ponds,	and	swamps.	You	will	have	a	high	likelihood	of	finding	egg	masses	the	next	morning if	

you	heard a	chorus	in	that	location	the	night	before.	Look	for	gelatinous	clumps	with	black	dots	in	the	center (see	

pictures above). Egg	masses	float	on	the	surface	or	may	be	attached	to	branches/plants	near	the	surface.	Dip	your	

container	below	the	egg	mass	and	scoop	it	up	with	water.	Try	not	to	shake	or	disrupt	the	egg	mass.	

Tadpole	care:	Tadpoles	are	very	easy	to	maintain which	makes	this	an	ideal	classroom	“pet”	and	activity.	Tadpoles	feel	

very	vulnerable	out	in	the	open	and	would	love	some	hiding	places	in	their	tanks.	A	few	rocks/leaves	from	outside	will	

be	excellent.	Since	they	are	cold-blooded,	placing	them	in	a	sunny	window	location	will	help	keep	them	warm.	After	

hatching	(~2-7	days)	they	will	feed	for	a	couple	days	on	remaining	yolk	(during	this	stage	they	will	be immobile)	and	will	

begin	foraging	after they start to	swim	freely.	Depending	on	the	species	that	you	collect,	they	may	take	between	1.5	

months	to	3	months	to	fully	develop.	They	can feed	on	boiled	spinach	(thaw from	frozen)	or	fish	flakes	(feeding	should	

be	standardized	between	the	tanks	to	avoid	confounding	your	results). They	do	not	need	extra	oxygen	into	the	water	as	

they	can	gulp	air	if	necessary.	Froglets	will sprout	back	legs	first	and	will remain	bipedal	in	the	water	for	several	days

until	the	front	limbs	emerge.	They	will	climb	out	of	the	water	and	onto	the	side	of	the	tank	and	begin	to reabsorb	their	

tails	in	the	final	stages	of	metamorphosis.	It	would	be	ideal to	pull	these	individuals	out	and	place them	in	a	separate	

container	lined	with	a	moist	paper	towel.	These	frogs are	now	ready	to	be	released	back	to	the	wild,	and	should	be	kept	
in	a	moist	container	until	you	return	them	to	the	wetland.	They	will not	eat	for	a	couple	days	after	emerging	but	prompt	

release	is	best.	

Note:

1. There	is	a	chance	that	the	egg	mass	you	collect	will	not	develop as	fertilization	is	external	and	not	always	

successful.	

2. Be	careful	about	allowing	students	to	touch	the	tadpoles/frogs	as	they	are	very	small	and	fragile.	Frog	skin	easily	

tears	and	limbs	are	easily	broken.	

3. If	the	water	becomes	dirty	and	you	decide	to	change	it: if	you	use tap	water,	be	sure	to	dechlorinate	it	first	

(dechlorinators	are	available	at	any	pet	store).	Untreated	pond/lake/wetland	water	can	be also used	to	

replace/supplement	the	water	in	the	aquarium.	

Appendices:

Suggested	Lab	Report	Grading	Rubric:	25	possible	points.	

Points Introduction	 Experimental	

Design

Results Conclusion/Discussion Grammar	and	

Spelling

5 Well	researched,	

excellent	

comprehension	

of	material,	

hypothesis	clearly	

stated	

Students	relate	design	

to	specific	question.	

Protocols	outlined	

clearly.

Students	show	

understanding	of	

experimental	concepts	

like	standardization,	

replication,	etc.	

Students	have	labeled,	

legible	graph	of	correct	

data	with	figure	caption	

that	explains	graph	and	

data.

Students	demonstrate	

comprehension	by	linking	

results	back	to	original	

hypothesis	(i.e.	Original	

hypothesis	was	supported	

or	not).	

Students	discuss	natural	

selection	implications	of	

osmotic	balance	using	

their	results.	

<3	errors

4 Decent	

background,	

moderate	

understanding,	

hypothesis	clearly	

stated

Students	detail	

experimental	design	but	

do	not	link	to	

hypotheses.	

Protocols	outlined.

Some	understanding	of	

experimental	concepts.

Neat	and	clean	graph	with	

correct	data.	Graph	has	

figure	captions	but	no	axis	

labels.

Students	link	results	to	

hypothesis	but	do	not	

clearly	state	whether	they	

hypothesis	was	supported.	

Some	discussion	of	

implications	towards	

natural	selection.	

<6 errors

3 Some	

background,	little	

understanding,	

hypothesis	

mentioned

Students	poorly	

communicate	

experimental	design,	

protocols	barely	

mentioned,	little	

understanding	of	

experimental	concepts.

Graph	does	not	have	

proper	data	or	mixed	up	

axes.	Graph	is	missing	

labels	or	figure	caption	as	

well.	

Students	do	not	link	

results	to	hypothesis,	

merely	restate	methods	

and	results.	

Little	or	no	discussion	of	

broader	concepts.

<9	errors

2 Little	background	

information,	little	

comprehension	

of	the	topic,	no	

hypothesis	

Experimental	design	is	

protocols	only	with	no	

indication	that	students	

understand	reasoning	

behind	the	design	or	its	

relationship	to	

hypothesis.

Graph	is	incorrect	data,	

lacks axis	labels,	figure	

captions,	etc.	

Students	repeat	previous	

sections	with	zero	

discussion	of	implications	

or	relationships.

<12	errors

1 No	background	

research,	very	

little	

comprehension,	

no	mention	of	

hypotheses

Experimental	design	is	a	

picture	or	diagram	with	

little	or	no	text	

explaining	protocols.	

Hypothesis	not	

mentioned.

Graph	is	illegible	or	

absent.

Students	demonstrate	

little	understanding,	do	

not	link	the	sections	

together,	do	not	make	any	

broader	inferences	on	

work.	

>13	errors