Monday, May 27, 2013

Brine Shrimp Hatching Lesson

Lesson: Brine Shrimp Hatching - Taught February 19, 2013

Work collaboratively with other students to set up a controlled experiment to answer the question:
What is the optimum salinity (salt level in water) for brine shrimp eggs to hatch?

4-5 INQB Investigate (Inquiry) Scientists plan and conduct different kinds of investigations, depending on the questions they are trying to answer.
4-5 LS1C (Life Science) Certain structures and behaviors enable animals to respond to changes in their environment.

Anticipatory Set: Looking at Brine Shrimp Eggs in their dormant stage using a magnifying glass.
-Prepared in advance 28 cups and lids w/ 1 mini-spoon of brine shrimp eggs and a magnifying glass.
“What do these brine shrimp eggs need to hatch?”

In Science Journals:
1. Discuss the Question, Background Research, and Hypothesis students started last week.
2. Distribute copies of Materials List and Procedure for the Investigation (see attached).
3. Students identify controlled variable, manipulated variable and responding variable.
4. Preview the list of procedures/ directions.

Label cups (Pre-prepared labels)

Distribute salt (Pre-prepared: cups of salt w/ 5ml spoons)
Students put in the correct amount of salt in each cup
Line the cups up in order and take a picture with iPod
iPods go in “Time out tubs” and put to the side for next step

Restate: “What type of variable is the water?” (controlled)
“IMPORTANT: only 150 ml of water in each cup. How much?”
Distribute water
(Pre-pared: cups of water, 150 ml measuring cups, stirring rods)
Students pour in 150 ml of water in each cup and stir
Line the cups up in order and take a picture with iPod
iPods in “Time out tubs” and put to the side for next step

Store cups on trays in the window for follow up next few days.

“What type of experiment are we conducting?”
“What question are we trying to answer?”

If time: Set up Science Journals to Record Data for the next 2 days.


Brine Shrimp Eggs (______________________   variable)

Salt                          (______________________   variable)

Water                       (______________________   variable)
4 congruent cups with lids
Magnifying glass
5ml spoon to measure salt
100 ml measuring cup to measure water
Camera (optional)


Getter # 1 – Get Tray
1.     Tape brine shrimp eggs sample in Science Journals.
      Put 1 mini-spoon of brine shrimp eggs in each cup (already done).

Getter #2 – Get Salt with 5 ml spoon
2.     Label the cups and ADD SALT in varying staged amounts:
Cup 1: 0 spoonfuls of salt (0 ml)
Cup 2: 2 spoonfuls of salt (10 ml)
Cup 3: 4 spoonfuls of salt (20 ml)
Cup 4: 6 spoonfuls of salt (30 ml)

Getter #3 – Get Water and Measuring Cup
3.     Add 150 ml of water to EACH cup
     Gently swirl to dissolve the salt.

Returner –
4.     Put Lids on and store the cups in a safe place.
Clean up other materials

5.     Record results on Day 2 and Day 3

This was a very successful lesson. The students were engaged throughout the lesson. The time and forethought I put into prepping the lesson paid off! If I were to teach this lesson again, I would definitely prep the materials in advance, as I did this time. It saves so much time in the distribution process. I would also use the same handout as it laid out clear and specific tasks for the students.

Looking back, it probably would have been better to use the doc cam to show students how to measure the salt, especially the process of starting on the flat edge to scrape of the excess salt. I wasn't sure students would see the flat/ levelness of the spoon under the doc cam. If I were to teach this lesson again I would use the doc cam to show the process, and then walk the spoon around to show the flat level.

Here is the evidence I observed that I met my objective: When it was the students turn to work, I observed the majority of student taking turns (working collaboratively) to measure the salt and the water. Sometimes, a few students wanted to do most of the work and needed some gentle reminders to share responsibility. For instance, one student was trying to measure water for a second cup, although he had already measured water and the other students were asking for the opportunity to measure. Another student wanted to measure all the salt in the cup that required the most salt. They responded well to gentle reminders to work together.

For the controlled experiment portion I noticed the varying amounts of salt (manipulated variable)  in all the cups before the students took their first picture, and that all the cups had same amount of water (controlled variable) after they took their last picture. I can use their iPods as an assessment tool; to make sure they took the pictures, and that the measurements were correct. I may not have iPods in a future classroom, so I would have to take that into consideration if teaching this lesson in the future.

I decided to say "stop, freeze, look at me" just as they were beginning to measure the water rather than use the "scientists" signal, because most students were working well and I wanted to share a quick piece of information without disrupting their work too much ("DO put water in the cup labeled 0ml"). In other words, I did not want them to have to completely empty their hands to hear that tidbit of information. 

When I am not teaching science, I often use two signals to get students attention. Usually, I say"1, 2, 3 Eyes on me" Students say, "1,2 eyes on you, hands folded too." This is similar to the "Scientists?" cue as I can quickly scan the classroom and see who has their hands folded, which prevents students from playing with papers, etc. when I am giving instruction. Sometimes I say, "Stop, freeze, look at me" and I scan the room for eyes and no movement. I find that useful for giving quick information I may have forgotten to mention, or when I realize something should be clarified. I do need to work on making sure I have 100% of students' attention 100% of the time I ask for it, and I need to follow up with restating expectations when necessary. 

Another practice I have been implementing into my teaching purposely includes wait-time and choral responses. I will thrice ask a question that requires a one or two-word response. I tell students "Raise your hand if you know it. Don't blurt it out" between each time I ask the question, and I will raise my hand at this point. Then, I will say, "When I drop my hand, whisper it if you know it." This encourages all to participate, without being disruptive. 

During the lesson, I realized the salt was not going to dissolve with simple swirling. So, I would definitely plan to distribute Popsicle sticks as part of the lesson next time. 

After the lesson, I was able to repeat the procedure with a couple of students who had been pulled out. As a full time teacher, I would offer the opportunity to students who may have missed a lesson to repeat it during lunch recess, or before or after school. 

The students looked for the brine shrimp eggs to hatch over the following days. They did not notice anything until Friday. They were so small; the size of a comma. I had a hard time noticing them. If I were to teach this lesson in the future, I would actually teach it on a Friday, rather than a Tuesday to allow the brine shrimp time to hatch over the weekend. 

As a full time teacher, I plan to teach Science on Fridays. Students will think it is "Fun Friday" because science is so engaging. They might not realize how much they are actually learning!

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