Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 948 · 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 of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) turmeric powder (d) a small bowl
2. 2.⚖️ 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
3. 3.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) reading the message
4. 4.⚖️ 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
5. 5.True or false: cutting the lemon is a job a child can do. (a) False (b) True
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice
7. 7.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) cutting the lemon
9. 9.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
10. 10.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
11. 11.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) writing the message (d) reading the message
12. 12.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
13. 13.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) putting the iron away (d) plugging in the iron
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a small bowl (d) a cotton bud
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
16. 16.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
17. 17.⚖️ 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
18. 18.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
19. 19.🔮 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
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
21. 21.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
25. 25.⚖️ 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
26. 26.True or false: ironing the paper is a job a child can do. (a) False (b) True
27. 27.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) turmeric powder (d) a magnet
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
29. 29.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
31. 31.⚖️ 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 kind of juice (c) the ironing time (d) how dark the writing is
32. 32.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
33. 33.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a balloon (d) a cotton bud
35. 35.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
36. 36.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
37. 37.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) writing the message (d) putting the iron away
40. 40.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed

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