Exercises in Science
..............Jack Kimball.............

Contrasting Differences


to contrast / contrasting : to describe/describing differences

to exercise : to do physical training, such as swimming or jogging

case : occurrence, example

development : the process of being made or becoming

dissimilar : not similar, unlike

to differ : to be dissimilar

diluted : weakened, made less strong

in proportion to : in relationship with something comparable in size or number

manufactured : made

atomic number : the number of protons in the center of the atom


Contrasting Differences

When scientists compare two or more concepts, in addition to similarities, they are usually interested in contrasting differences. Contrasting differences is a powerful way to discover new ways of looking at data. Consider the following.

Among people aged 65 who do not exercise there are twice as many cases of heart disease as among people who exercise daily.

The information above indicates that there is a big difference in the development of heart disease between people who exercise regularly and those who don't. It is interesting to see in this example that at age 65 the number of cases of heart disease among those who do not exercise is much more than for those who exercise daily.

Sentence Patterns and Vocabulary


Among those who exercise and those who don't, the number of cases of heart disease{is different / is not the same / differs.


Case X {differs from / is different from / is not the same as / is in contrast with} case Y.


X and Y {are different / are not the same / are dissimilar / differ.


Unlike / In contrast with / In comparison with / Compared to} substance Y is {soft / heavy / diluted.


Substance X is{softer / heavier / more diluted}than Y.

Substance Y is not as
{soft / heavy / diluted}as X.

Other Words and Phrases Used for Contrasting Differences

while...., yet/but difference
whereas...., however dissimilar
although/though...., nonetheless on the other hand
even though...., nevertheless in contrast

Exercise 1
Read the following and underline words and phrases used to contrast differences.

The weight of the brain in proportion to the weight of the 1/50th body differs among animal species. While the weight of an elephant's brain is heavier than the brain of an adult human, in relationship with the elephant's brain is only 1/1000th of its body weight. In contrast, the human brain is 1/50th of an adult's body weight. In proportion to body weight, the elephant's brain is lighter than the human brain.


Light passenger aircraft and jetliners are quite dissimilar. Although light passenger airplanes carry passengers, they carry fewer passengers than jetliners. As the name suggests, the light passenger airplane is not as heavy as the jetliner. This means that the lighter aircraft is simpler to build and easier to operate than the jetliner. Whereas the jetliners designed to fly long distances, the light passenger aircraft flies shorter distances and not as many hours as the jetliner.

Exercise 2

Read the following and write in words and phrases that contrast differences.

1) Cats and dogs are _________________ species.

2) In most computers ROM (Read Only Memory) ____________________ RAM (Random Access Memory) in the way it handles memory.

3) _____________________ other vitamins, Vitamin D is manufactured by the body after exposure to sunlight.

4) Humans are ____________________ elephants.

5) _____________________ Venus and Earth have being outside in daylight atmospheres, there is no life on Venus.


Comparing and Contrasting

When we compare two or more concepts, manufactured products or natural phenomena, we most often look for similarities and differences. When we write about these concepts, products and phenomena, we often compare and contrast them at the same time.

Read the following.

(1) The elements phosphorous (P) and silicon (Si) have numerous similarities and differences. (2) They are both nonmetallic elements with comparable atomic numbers. (3) Neither number is high: silicon's atomic number is 14 and phosphorus's number is 15. (4)Their melting points are also parallel: the melting point of silicon is 1410°C and that of phosphorous is 1554°C. (5) Nonetheless, phosphorous and silicon are dissimilar in many ways. (6) Phosphorous is a yellow, waxy solid, whereas silicon often appears in a brown crystalline form. (7) Phosphorous is used in fertilizers and detergents, but silicon, in contrast, is used in semi-conductor devices.

In the above paragraph, Sentence 1 serves as the topic sentence, declaring that there are points of comparison and difference. Sentences 2-4 compare similarities and Sentences 5-7 contrast differences.

Exercise 3
Review the words and phrases for comparing similarities and contrasting differences. Then, for a, b, and c (below) write one or two sentences that connect the ideas. Use words that compare and contrast.

(a) A nighthawk and sea gull are birds. A nighthawk flies at night. A sea gull flies in daytime. The nighthawk has grey and brown feathers, the sea gull has grey and white feathers.

(b) Spinach and daikon are vegetables. Spinach is green and has big leaves. Daikon is white and has a long root. Spinach is eaten uncooked or cooked. Daikon is often eaten after it is cooked.

(c) Botany and zoology are sciences. They are branches (or subfields) of biology. Botany is the study of plants. Zoology is the study of animals.


Writing Exercise

Japanese puffer-fish or fugu have a backbone, brain and liver. Human beings have a backbone, brain and liver. The fugu and humans have immune systems. But there are many differences! Write a paragraph that compares similarities and contrasts differences between these two species.