Integrated Topic Four

Topic Four – “Tree Frogs’ Self-Cleaning Feet Could Solve a Sticky Problem.”

Lesson Four examines a research project involving Tree Frogs. In this lesson you will learn some strategies for understanding unfamiliar words before we write our essay.

Word Clues

In the article there are a number of academic words that may be unfamiliar to you. Instead of using a dictionary, there are some other options that can be used to understand difficult words. If we look at the context of a sentence, we can find word clues that can help us discover their meanings.

There are four common types of word clues we want to look.

  1. Synonyms
  2. Antonyms
  3. Examples
  4. Common Sense

A Synonym is a word that has almost the same meaning as another word. What do you think the synonym is for buy in the following sentences?

“He made too many purchases already this month. He will have to stop buying so many things.”

In the sentence the word purchase is a synonym for buy.

Another clue is an Antonym. This is a word that means the opposite of another word. Words such as but, in contrast, and however are used to signal an antonym.

What do you think sedentary means in the following sentence?

“The doctor told him that he needed to change his sedentary lifestyle and become more active.”

In the sentence the word active helps us understand that sedentary means inactive – someone who sits much of the time.

A writer may use Examples of unfamiliar words that can help us understand the meaning. In the following sentence what do you think the word cling means from the example?

“Tree Frogs can cling to a vertical surface, so they can easily climb walls.”

The sentence uses the example of climbing walls to help us understand the word cling.

The last clue is Common Sense. To use this clue we need to look at the whole sentence carefully. Other information in the sentence will often help us understand the meaning. Look at the following sentence and see if you can understand the word evidence.

“Researchers look for evidence that can help them understand and answer difficult questions.”

If researchers want to understand and answer difficult questions, what do they look for? The sentence strongly suggests that evidence means something that can answer difficult questions

Reading Task

Directions: Read the following article. Using Word Clues, try to guess at the meaning of unfamiliar words. Take notes as you read.  Before reading the passage, read carefully the topic question below.

Topic Question: Using the information provided by the writer, explain how the feet of Tree Frogs are self-cleaning.

Tree Frogs’ Self-Cleaning Feet Could Solve a Sticky Problem

ScienceDaily (July 4, 2011) — Tree frogs have specially adapted self-cleaning feet which could have practical applications for the medical industry.

“Tree frog feet may provide a design for self-cleaning sticky surfaces, which could be useful for a wide range of products especially in contaminating environments — medical bandages, tyre performance, and even long lasting adhesives,” says researcher, Niall Crawford at the University of Glasgow who will be presenting this work at the Society for Experimental Biology Annual Conference in Glasgow on 3rd of July, 2011. Tree frogs have sticky pads on their toes that they use to cling on in difficult situations, but until now it was unclear how they prevent these pads from picking up dirt. “Interestingly the same factors that allow tree frogs to cling on also provide a self cleaning service. To make their feet sticky tree frogs secrete mucus, they can then increase their adhesion by moving their feet against the surface to create friction. We have now shown that the mucus combined with this movement allows the frogs to clean their feet as they walk,” says Mr. Crawford.

The researchers placed the White’s tree frogs on a rotatable platform and measured the angles at which the frog lost its grip. When the experiment was repeated with frogs whose feet were contaminated with dust they initially lost grip but if they took a few steps their adhesive forces were recovered. “When the frogs did not move the adhesive forces recovered much more slowly,” says Mr. Crawford. “This shows that just taking a step enables frogs to clean their feet and restore their adhesion ability.”

White’s tree frogs have tiny hexagonal patterns on their feet, which allow some parts of the pad to remain in contact with the surface and create friction, whilst [while] the channels between allow the mucus to spread throughout the pad. This mucus at once allows the frog to stick and then, when they move, also carries away any dirt. If this can be translated into a human-made design it could provide a re-useable, effective adhesive. Retrieved on July 31, 2011, from


Write a 300-400 word essay on the topic above.

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