Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 633 · 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 mirror is needed for the secret lemon message. (a) True (b) False
2. 2.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) writing the message (d) putting the iron away
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a mirror (c) lemon juice (d) a small bowl
4. 4.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) white paper (d) a battery cell
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a battery cell (d) white paper
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
10. 10.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) reading the message (d) putting the iron away
11. 11.True or false: reading the message is a job for an adult. (a) True (b) False
12. 12.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a magnet (d) a small bowl
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
17. 17.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
18. 18.⚖️ 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
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a cotton bud (d) yeast
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
21. 21.⚖️ 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
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
23. 23.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) reading the message
24. 24.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
25. 25.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
26. 26.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
27. 27.True or false: yeast is needed for the secret lemon message. (a) True (b) False
28. 28.True or false: ironing the paper is a job a child can do. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice (d) the iron setting
31. 31.True or false: cutting the lemon is a job a child can do. (a) True (b) False
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
34. 34.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
36. 36.True or false: writing the message is a job for an adult. (a) True (b) False
37. 37.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) white paper (d) a small bowl
39. 39.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
40. 40.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) putting the iron away

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