Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 143 · 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 not needed for the secret lemon message. (a) False (b) True
2. 2.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) writing the message (d) dipping the cotton bud
3. 3.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air
5. 5.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) writing the message
6. 6.⚖️ 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
7. 7.True or false: reading the message is a job for an adult. (a) False (b) True
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a mirror (d) a balloon
9. 9.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the iron setting (c) how dark the writing is (d) the same cotton bud
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
12. 12.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
13. 13.🔍 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
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the ironing time (d) the kind of juice
15. 15.🛟 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
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
18. 18.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
19. 19.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
20. 20.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) putting the iron away (d) cutting the lemon
21. 21.True or false: writing the message is a job for an adult. (a) False (b) True
22. 22.🍋 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) reading the message
23. 23.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
25. 25.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
26. 26.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) turmeric powder (d) white paper
29. 29.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
30. 30.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
31. 31.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) writing the message (d) letting the paper dry
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, if shaken (d) yes, in the dark
34. 34.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a mirror (d) an adult with an iron
36. 36.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) yeast (c) white paper (d) an adult with an iron
38. 38.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
39. 39.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
40. 40.⚖️ 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

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