Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 469 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a magnet (d) yeast
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
4. 4.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
5. 5.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
8. 8.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) letting the paper dry (d) writing the message
9. 9.True or false: plugging in the iron is a job a child can do. (a) True (b) False
10. 10.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
11. 11.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) ironing the paper
12. 12.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) white paper (d) a mirror
15. 15.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
16. 16.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
17. 17.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
18. 18.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
19. 19.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
20. 20.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
21. 21.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
22. 22.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
24. 24.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) writing the message
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a small bowl (d) turmeric powder
26. 26.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
29. 29.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a battery cell (d) turmeric powder
30. 30.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) white paper (d) an adult with an iron
32. 32.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) reading the message
33. 33.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) letting the paper dry
34. 34.True or false: letting the paper dry is a job a child can do. (a) True (b) False
35. 35.True or false: reading the message is a job for an adult. (a) True (b) False
36. 36.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
37. 37.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) reading the message
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
39. 39.True or false: plugging in the iron is a job for an adult. (a) False (b) True
40. 40.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False

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