Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 50 · 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.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
3. 3.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) letting the paper dry
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) white paper (d) lemon juice
5. 5.⚖️ 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
6. 6.True or false: writing the message is a job for an adult. (a) False (b) True
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) white paper (d) a small bowl
8. 8.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) ironing the paper (d) plugging in the iron
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) reading the message
12. 12.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
13. 13.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) yeast (d) an adult with an iron
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a mirror (d) lemon juice
18. 18.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
19. 19.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) lemon juice (d) a magnet
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
21. 21.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
22. 22.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a battery cell (d) a small bowl
23. 23.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
24. 24.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) plugging in the iron
25. 25.True or false: putting the iron away is a job a child can do. (a) False (b) True
26. 26.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
27. 27.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) an adult with an iron (d) white paper
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) the same cotton bud (d) how dark the writing is
33. 33.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) putting the iron away (d) plugging in the iron
34. 34.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
35. 35.⚖️ 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) False (b) True
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a cotton bud (d) yeast
37. 37.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) writing the message (d) cutting the lemon
38. 38.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) dipping the cotton bud (d) putting the iron away
39. 39.True or false: reading the message is a job for an adult. (a) False (b) True
40. 40.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) dipping the cotton bud

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