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Pond Eggs Under the Microscope

Grade 8 practice comparing frog, snail, fish, chicken and human embryos to infer relationships not seen in adult anatomy.

Grade 8ScienceInteractive · Printable

Aligned toMS-LS4-3

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
9 questions
Classroom-ready

Details

Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Circle the answer, Sorting, Short answer

About this worksheet

What students practice

Students compare features of early embryos across species using observations and a data table.
Students use embryo evidence to infer relationships that adult anatomy does not show.

How to use

Read the class notes together and have students point to each feature in the table; let them work the questions alone, then discuss the written argument.

Curriculum

NGSS standard covered

MS-LS4-3

Compare patterns in embryo development across species to find relationships not seen in adult anatomy.

Preview

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Pond Eggs Under the Microscope

Compare early embryos to find relationships that adult bodies hide.

Part 1: What the class saw

Read the passage and Mateo's notes, then answer the questions.

Eggs from the School Pond

1Each spring, Mr. Ekwueme's eighth-grade class collects a few eggs from the pond behind the school with a permit from the county, then returns the young animals to the pond after the study. This year Mateo Szabo's group took one small clump of leopard frog eggs and a jelly capsule of pond snail eggs. The group kept the eggs in pond water in a classroom tank at about 18 °C and looked at them through a microscope every day.

2An embryo is an organism in its earliest stage of development, before it hatches or is born. Mateo's group noticed that the frog embryos changed shape quickly. A round ball of cells stretched into a long body, a bump grew at the back end and small bumps appeared just behind the head. The snail embryos changed too, but in a different way: a tiny coiled shell formed, and Mateo never saw bumps along the neck or a bump at the back end. Each day, one student drew what the group saw while another wrote short notes, and they compared drawings to make sure they agreed. They counted the morning the eggs were collected as day 1. Mr. Ekwueme reminded everyone to move eggs gently with a plastic spoon and to wash their hands after touching pond water.

3Mr. Ekwueme then gave the class a chart from biologists who study embryos. It compares early embryos of a fish, a frog, a chicken, a human and a pond snail. Early on, the four animals with backbones each have a row of folds in the neck region, called pharyngeal arches, and a tail that sticks out past the hind end of the body. What those parts become depends on the animal. In fish, the arches develop into gills. In chickens and humans, they develop into parts of the jaw, ear and throat, and in humans the tail shrinks to a small tailbone.

4The adults of these animals look very different from one another. A fish has fins and gills, a chicken has feathers and a beak, and an adult human has no gills and no tail that anyone can see. Mr. Ekwueme asked the class a question to think about: if the adults are so different, why would their embryos share the same features?