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Browse through our collection of theory images and stock photos. They are all royalty-free and ready to use for your next project.

Price is in US dollars and excludes tax

129 stock photos

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Young teacher or student draw triangle on a blackboard with formula

Young teacher or student draw triangle on a blackboard with formula

$7
Young teacher or student draw triangle on a blackboard with formula

Young teacher or student draw triangle on a blackboard with formula

$7
row of pink blank notes in different states isolated on black

row of pink blank notes in different states isolated on black

$5
young happy students studying at home

young happy students studying at home

$5
group of young happy students studying at home and looking at camera

group of young happy students studying at home and looking at camera

$5
office stationery items desk creative workshop

office stationery items desk creative workshop

$5
office stationery items desk creative workshop

office stationery items desk creative workshop

$5
Man in tinfoil helmet watches TV, ufo phobia

Man in tinfoil helmet watches TV, ufo phobia

$5
top view of paper rubbish with electric bulb drawn on blackboard

top view of paper rubbish with electric bulb drawn on blackboard

$5
Maths formulas written by white chalk on the blackboard background.

Maths formulas written by white chalk on the blackboard background.

$5
Maths formulas written by white chalk on the blackboard background.

Maths formulas written by white chalk on the blackboard background.

$5
Stressed young man with tin foil hat thinking in the bedroom

Stressed young man with tin foil hat thinking in the bedroom

$5
young bored woman studying while her friend dancing on bed

young bored woman studying while her friend dancing on bed

$5
Entering Area 51 Sign

Entering Area 51 Sign

$5
Brilliant mathematician reviewing his work and thinking

Brilliant mathematician reviewing his work and thinking

$9
Young smart mathematician drawing on the chalkboard

Young smart mathematician drawing on the chalkboard

$9
Improve company quality

Improve company quality

by adam121
$5
Human hand holding and reading book for research

Human hand holding and reading book for research

$5
Group of dice close up on dark black background

Group of dice close up on dark black background

$5
Back to school.

Back to school.

$5
Close-up of cards for studying music and piano in the phone.

Close-up of cards for studying music and piano in the phone.

by puhimec
$5
Music theory lesson, solfeggio using educational flashcards.

Music theory lesson, solfeggio using educational flashcards.

by puhimec
$5
A little girl learns notes using the piano keys on the phone.

A little girl learns notes using the piano keys on the phone.

by puhimec
$5
Hand playing piano on wooden table

Hand playing piano on wooden table

$5
Man playing guitar composing

Man playing guitar composing

$5
Blackboard with math lesson written on it

Blackboard with math lesson written on it

$5
Blackboard with math lesson written on it

Blackboard with math lesson written on it

$5
Numerology Numbers Concept. Numerology Calculate Life Path and Destiny Numbers. Many pebble stones

Numerology Numbers Concept. Numerology Calculate Life Path and Destiny Numbers. Many pebble stones

$5
Cyber safety and machine learning concept. Funny robots, black chalkboard handwritten text.

Cyber safety and machine learning concept. Funny robots, black chalkboard handwritten text.

$10
group of young bored students studying at home

group of young bored students studying at home

$5
Experiments