### Elastic Maths

How do you write a computer program that creates the illusion of stretching elastic bands between pegs of a Geoboard? The answer contains some surprising mathematics.

### Logic, Truth Tables and Switching Circuits Challenge

Learn about the link between logical arguments and electronic circuits. Investigate the logical connectives by making and testing your own circuits and fill in the blanks in truth tables to record your findings.

### Truth Tables and Electronic Circuits

Investigate circuits and record your findings in this simple introduction to truth tables and logic.

# Big and Small Numbers in the Living World

### Why do this problem ?

Practice with the use of numbers is a crucial biological skill. These interesting questions will allow you to practice these skills whilst developing awareness of orders of magnitude in scientific contexts.

### Possible approach

There are several parts to this question. The individual pieces could be used as starters or filler activities for students who finish classwork early. Enthusiastic students might work through them in their own time. Since there is no absolutely 'correct' answer to many of these questions, they might productively be used for discussion: students create their own answers and then explain them to the rest of the class. Does the class agree? Disagree? Is there an obvious best 'collective' answer?

### Key questions

• What assumptions will you need to make in this question?
• How accurate do you think you answer is?
• What order of magnitude checks could you make to test that your answer is sensible?

### Possible extension

Can students make up similar questions? Can they put any upper or lower bounds on the numbers?

### Possible support

Students might struggle with the 'open' nature of the questions. To begin, they might like to read the Student Guide to Getting Started with rich tasks