Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 608 · 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.⚖️ 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 measure it (c) we keep it the same
2. 2.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) a magnet
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
5. 5.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
7. 7.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
9. 9.True or false: yeast is needed for the secret lemon message. (a) True (b) False
10. 10.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) letting the paper dry (d) writing the message
11. 11.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) an adult with an iron (d) a battery cell
13. 13.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a balloon (d) white paper
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
16. 16.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
17. 17.⚖️ 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) True (b) False
18. 18.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
20. 20.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
23. 23.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
24. 24.True or false: writing the message is a job a child can do. (a) False (b) True
25. 25.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) writing the message
26. 26.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) a magnet (d) yeast
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
29. 29.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
30. 30.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
31. 31.⚖️ 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
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the iron setting (c) the same paper (d) the kind of juice
33. 33.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
34. 34.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
35. 35.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
36. 36.⚖️ 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) True (b) False
37. 37.True or false: ironing the paper is a job for an adult. (a) True (b) False
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) yeast
39. 39.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the ironing time (c) the kind of juice (d) how dark the writing is

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