Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 279 · 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.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
2. 2.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a magnet (c) white paper (d) a cotton bud
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same cotton bud (c) how dark the writing is (d) the same paper
5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
6. 6.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a battery cell (d) a cotton bud
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
8. 8.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) putting the iron away
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
10. 10.True or false: reading the message is a job for an adult. (a) True (b) False
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
12. 12.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
16. 16.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) writing the message
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
18. 18.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
19. 19.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) ironing the paper (d) putting the iron away
20. 20.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
22. 22.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) plugging in the iron (d) cutting the lemon
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a mirror
25. 25.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the ironing time
27. 27.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) cutting the lemon
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a magnet (d) a cotton bud
30. 30.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
31. 31.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) physical (d) musical
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
33. 33.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a balloon (d) a small bowl
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
36. 36.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) putting the iron away (d) dipping the cotton bud
37. 37.⚖️ 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) False (b) True
38. 38.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
39. 39.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
40. 40.True or false: putting the iron away is a job a child can do. (a) True (b) False

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