Summary

This whiteboard activity is designed to teach students the structure and functions of the digestive system. At the end of this lesson, students will be able to recall names of digestive organs and the enzymes they produce or contain. They will be able to explain how their food is digested.

Suitable for

Mainly year 8, but also useful for years 7 and 9.

Using a non-interactive whiteboard

Animations would need to be activated with the mouse rather than the light pen.

Prior learning required

Students should already know that we need a healthy balanced diet and what this contains. They will have a basic concept of the need to chew food properly and that when it is swallowed it travels down into the stomach, though some students will not distinguish between the stomach, intestines and belly or abdomen.

Aims and objectives

At the end of this lesson students should understand how the digestive system turns the food we eat into chemicals that can be absorbed into the bloodstream. They should be able to label a diagram of the human digestive system and explain what each digestive organ does.

Timings

Take about 20 minutes to go through the activity without students taking notes in the first instance. Then have a quick question and answer session to see how much information the students can recall. This should take about five minutes. Now ask the students to label a diagram of the human digestive system. They should then make some notes on each organ in the system. They should be allowed 15 minutes to complete this using the whiteboard, going to various frames as individual students need them. You can skip backwards and forwards as necessary. Finally take about 15 minutes to discuss one of the suggested group activities and then set it as a homework task.

Suggestions for group activities

The whiteboard may be used in a number of ways according to your needs. It could be used as one of the following.

1. A superior "chalk and talk" lesson with the timings given above.
2. A recall session for year 9 students to introduce the healthy living topic - it would take about 10 minutes to skim through the materials.
3. An interactive revision session for students. The teacher should ask questions about what happens in each region of the digestive system.
4. A presentation tool for use by a small group of students who have spent about 15 minutes going through the whiteboard materials and seeking clarification from the teacher. It might take about 20 minutes according to ability.
5. A research tool used by individuals, groups or the whole class.

Suggestions for differentiation

For more able students, teachers should also explain that food contains chemicals that are too big to get into our blood, such as starch, protein and fat, so these need to be broken down into glucose, amino acids, fatty acids and glycerol. Use scientific names for the intestines: ileum and colon. Explain that carbohydrase turns starch into maltose and that maltase turns maltose into glucose. Finally, explain that for growth and repair, amino acids are turned back into protein.

For the most able students, teachers should point out that food also contains mineral salts and vitamins that do not have to be digested because these molecules and ions are already small enough to be absorbed into the bloodstream.

For less able students, teachers should concentrate on the names of the digestive organs and emphasise the need to break large insoluble materials such as bread and meat into small molecules that can be absorbed into the blood.

Further activities

Make simple models of starch or protein using popper beads and show how enzymes chop these into smaller fragments. For example, carbohydrase chops starch (a poly-sugar) into maltose and maltase chops maltose (a di-sugar) into glucose (a mono-sugar).

Investigate the relationship between the surface area and volume of a tube and the effect on this ratio of increasing the length or diameter of the tube: the small intestine is long and narrow providing a large surface area for the absorption of digested food and the rectum is short and wide for storing a large volume of undigested fibre. Students could make cylinders from paper and then measure and calculate surface areas and volumes.  

Curriculum links

Science

Sc2 Life processes and living things

2 Humans as organisms
   Nutrition

QCA schemes of work units:
7I Energy resources
8A Food and digestion
9B Fit and healthy