Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 675 · 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 is the odd one out? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) reading the message
2. 2.⚖️ 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
3. 3.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
4. 4.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) a battery cell (d) a balloon
7. 7.⚖️ 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
8. 8.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the paper ate it (d) the ink is magnetic
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) writing the message
12. 12.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
13. 13.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
14. 14.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
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) True (b) False
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a balloon (d) lemon juice
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) white paper (d) a cotton bud
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) an adult with an iron (d) a small bowl
21. 21.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) cutting the lemon (d) putting the iron away
22. 22.True or false: white paper is needed for the secret lemon message. (a) False (b) True
23. 23.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) white paper (d) a balloon
25. 25.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a magnet (d) a small bowl
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
28. 28.True or false: cutting the lemon is a job for an adult. (a) True (b) False
29. 29.⚖️ 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
30. 30.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a cotton bud (d) a balloon
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
33. 33.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a magnet (d) lemon juice
35. 35.True or false: putting the iron away is a job for an adult. (a) False (b) True
36. 36.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
37. 37.True or false: putting the iron away is a job a child can do. (a) True (b) False
38. 38.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
39. 39.True or false: letting the paper dry is a job for an adult. (a) True (b) False
40. 40.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) writing the message

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