Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 987 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) it turned into air (d) the ink is magnetic
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the iron setting (d) the kind of juice
5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
7. 7.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a magnet (d) a battery cell
9. 9.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) reading the message
10. 10.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
11. 11.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
12. 12.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
13. 13.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
16. 16.⚖️ 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
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
18. 18.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
20. 20.⚖️ 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) False (b) True
21. 21.True or false: plugging in the iron is a job for an adult. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) letting the paper dry
23. 23.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
30. 30.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
32. 32.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) an adult with an iron (d) turmeric powder
34. 34.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) reading the message
35. 35.True or false: plugging in the iron is a job a child can do. (a) True (b) False
36. 36.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
37. 37.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a magnet (d) yeast
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
40. 40.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) cutting the lemon

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