#### Vector (Interval): Model the surface of the lake

The image shows lake Bracciano in Italy, which has an almost circular surface. Calculate the approximate area of the lakes surface. Fill out the answer fields below. All length units are in kilometers, the surface is in square kilometers. Round each to one decimal number. This task type is handy for tasks that could encounter rounding differences or whenever the user has to model or measure some quantity or size.

# Circle

Modeling
7

#### Interval: Surface area of a CD

Determine the surface area of one side of a CD. Identify the needed values in the task image or measure a CD you have at hand carefully. Insert your result in the answer field below. Give your result in $cm^2$ and round to one decimal place.

# Circle

Modeling
7

Berechnen Sie die Abstände zwischen Gerade und Punkt. 1.) $f(x)=3x-4$, $A\left(0,5\middle|2\right)$ 2.) $g(x)=-2x+2$, $B\left(-2\middle|1\right)$ 3.) $h(x)=-\frac{1}{4}x+2$, $C\left(2\middle|-1\right)$ Gib die Werte auf zwei Stellen hinter dem Komma gerundet an.

# Functions & characteristics

Training
11

#### The Chat

In the Digital Classroom, students and teachers can interact with each other via chat (speech bubble icon, see picture, left). Text and voice messages as well as pictures can be sent. Please send us a photo of your notes on the previous task or a text or audio message! Note: Sending messages via chat is only possible if you are working in the Digital Classroom and have an active internet connection.

# Unassigned

Learning
5

# Numbers & operations

Training
7

#### Rewarding, attempts, and support tasks

For a correct answer, the user is rewarded points. More than one wrong answer reduces the initially 100 points an exercise contributes. For every exercise, the user can try four times to enter the solution. So what is the solution here? Please try to find out. Maybe the hints will help...

# Numbers & operations

Learning
7